Surely it depends on the jurisdiction to which the plane is subject, just like with ships? The law of the country under whose flag the plane flies applies to everyone in the plane, just as it would on land. If that country specifies restrictions on photographing people you are bound by those. Airlines may presumably apply their own rules within that framework. You have no a priori rights on the basis of where you come from.
I am not a lawyer.
Apart from the legal aspect, I could imagine another reason why new policies concerning filming (and photographing) on board have been established:
There seems to be an increase in video footage of passengers and airline personnel in controversial situations (e.g. concerning enforcement of health-related mask mandates) going viral online in the last years. Maybe airlines want an easy way to at least control production of such footage.
Photos of people in airplanes specifically not permitted. […] Where is this coming from?
Typically, from the airline policy, as it’s the case in the US where airplanes are not considered public spaces:
Airlines have more power on planes because as private parties they are not bound by the First Amendment. "They are within their rights to establish these rules, they are within their rights to throw you off the aircraft if you continue filming," says Joseph Larsen, a media-law attorney in Houston.
Note that unlike planes, airports are considered public spaces in the US:
Lawyers who specialize in First Amendment or travel law say airlines generally cannot limit photography or video recording in an airport because it is a public space.
As Traveller mentioned, countries are increasingly restrictive about taking pictures in public spaces.
Credit:stackoverflow.com‘