Why weren't colonies accepted as part of their colonizing countries?

Do not underestimate how different was life before fast long distance communication and travel.

About Brazil: ~1820, Brazil had 6M people, 3M free + 3M slave. Portugal had 3M.

When Brazil was raised as part of the kingdom, there were deputies representing Brazil, but very few. People noticed that it was not fair, but fairness would demand that half the seats be given to Brazilians. Do you think a Portuguese would easily accept that half of his lawmakers come from the colonies? Besides that, it would take months for a Brazilian lawmaker to communicate effectively with his electors.

I am not sure about pops in the Spanish, French or English empires versus the metropolitan pop, but I guess it would be very relevant.

About US: everybody heard "no taxation with no representation", and this has a lot to do with the original colonial pact (Edmund Burke wrote a lot about this):

• US colonies would not pay tax
• US colonies would import/export only with England (monopoly)
• US colonies could not build some kinds of manufactories.

This happens because it would be very difficult for the King to tax a distant colony. Again, because any dispute would take months to be solved. It is easier to impose the monopoly and tax any commerce in the UK side.

Some people say that the taxes imposed by the UK before US independence were not so high, but the amount was not the point: any tax was too much if the monopoly and manufactory restrictions were still in place. And on the UK side, many people depended on the monopoly. It is not very surprising that after the wars commerce UK-US resumed in the XIX century, as the trade connections were already well established.

If suddenly there were fair representation (and taxation) for all the colonies, then how would all this change?

Some general comments:

Do you know the history of the cooperative of pig producers that started to help its members to produce chicken too? Suddenly there were conflicts over allocation of resources to pig problems against chicken problems, and the cooperative split. A parliament representing colonies and metropolis would have similar problems. Too many diverging interests. At least some kind of federation with local parliaments would be needed.

Some colonies are too small to be independent. During the independence of Brazil, there were people on the Grao-Para province (amazon river) and Angola which wanted to go with Brazil and others to remain in Portugal. But independence was not an option, as Angola depended on comerce, and Grao-Para, even in 1870 still could not have a profitable boat transportation system: they could not be independent with no subsidy from a metropolis. (Eventually Grao-Para went with Brazil, and the independence treaty stipulated that Brazil did not have a claim on Angola)

A similar reasoning is true for many small UK colonies. If a relative lack of representation is the price to pay for the economical and defense support from the metropolis, then let it be. And if a colonist is not a citizen in exactly the same way as a metropolitan, then strange convoluted citizenship, immigration and passport rules such as in the XX century british territories naturally emerge and even make some sense.

Another related XX century anecdote, to show that some people had reason in mistrusting some modern independence movements:

When Angola and Moçambique got independent, there were white or mixed race pops, some of them did not even remember when their antecessors come from Portugal to Africa. And everyone there could choose Portuguese citizenship and emigrate. Most of the black people fell for the communist promises of a new popular black government and stayed. But 800K people, mostly non-blacks, emigrated back to portugal, and many of them did not have any known relative in portugal anymore. This was almost 10% of portuguese population.

I have known 2 white (not really nordic-white, may be they are mixed race) families who at first decided to stay, as all their business and families were in Angola and Moçambique.

A shoe-maker in Moçambique had a two-store house, with his shop in the lower floor. After independence, the commie government come and stated that his house was now property of the "shoe makers communist association", that all his profits belonged to the government, and he could only take a fixed salary. As his fixed salary was ridiculous, he had to sell out of the books, and heavily bribe the commie who come every week to collect his profits, to turn his eye elsewhere. Then, he decided to leave to Portugal, still in time to collect his Portuguese citizenship, and start life from scratch. His son is today university professor at Coimbra.

A orange farmer: six months after independence all was nice. Then the commies come in tactical trucks, inspected the farm, and declared that the people committee would decide what to do. Life went on for some months. Then, the family went to a neighbor farm for a birthday party. Suddenly, their right-hand man, a black African, come pretty hurt and blooded: "the commies come, they killed every worker. I hide among the corpses, and when it was dark I ran. Lets all of us run! They know about this farm too!" So they went all to Namibia, where they were segregated from their black savior due to Apartheid laws. When moving, they could look back to see smoke raising from their farm: the commies just burned everything. They also had time to emigrate to Portugal and claim Portuguese citizenship. They regret very much that looking at Google Earth, their once lovely farm is now only savanna and ruins.

Do you really would want a peace that would grant parliament seats to those independence parties?

First, let's take your example of the UK. Ireland, Wales, Scotland and England are close to each other. Egypt, while not "that" far, is still quite far from the rest of the UK. Canada is even worse. Sudan wouldn't be so far if Egypt was part of the UK but then... France has quite a lot of trouble to gather the votes from La Réunion and the other Dom-Tom, it would be a political mess for the UK since many of the former colonized would be citizen.

Being citizen of the UK would have given, with some other things, the right to vote.

Colonist UK, didn't want this to happened. British people were at the height of their power, they thought they were superior in many ways to the natives, giving them the same rights would have caused an uprising in the heartland. In most case, it's kind of something you don't want to happened. In the early Twentieth century, the colonizing powers tried giving them more rights in order to appease tensions, it was quite recent as far as colonialism go, they had different ideologies than we had, and people like Rhodes were acclaimed as heroes.

For the Portuguese empire it's quite a weird case, they had quite a lot of instability at home after Napoleon's invasion, that's why they went to Brazil and started giving more rights and what's described in your link. It was a last resort, not something they wanted to do for a long time.

Thus, we covered a bit of the colonizing part of it.

Now for the colonized part. Most of the colonized people, had a different history than the colonists, Egypt for example fought a lot of war against people thralling them, against Greeks, against Romans, against Ottomans, against France ..., I'm not an expert on the British domination of Egypt but I'd be very surprised if they never intended to get their freedom again. Egypt was an incredible empire for a very very long time, they were a beacon of civilization for a long time and were almost always important before being subjugated by the Ottomans. They wanted back the gloriousness of past times, they did not want to switch masters.

Most colonized people didn't want to be part of the colonizing empire, Algeria didn't really reacted well to the French trying to make it part of France for good. One can say the deal proposed was not very fair but once again, the Colonizing powers were feeling that was fair, their ideologies were different, what they knew of them was limited, racism was kinda spread everywhere...

For the colonies like Canada, it's more of a special case than anything else. Colonists left their old countries for many reasons, be it promise of wealth, wanting to start over a new life, discovering etc... And these colonies always felt deprived compared to the heartland. Logistics were harsh to organize, phone and internet didn't exist so instant communication were kind of rare if you weren't on the same continent. Local administrators were usually left to their own devices, which made them more important to the people than their "true" overlord. The US didn't feel inferior the the UK, they wanted their freedom and got it. Why would Canada not want it ? Why would any other colony would want to stay shackled if one got free ?

I think the answer was not a lot.