Upvote:3
I believe the issue many swimming pools face is that not only is it becoming difficult to make the difference between actual swimming shorts and shorts you would wear in other circumstances, but many swimming shorts are actually designed to be usable for both (being very quick to dry, mostly).
So many of the younger people will just wear their swimming shorts all day long, and then go to the pool with those rather than bothering to change, which causes all sorts of hygiene and pool maintenance issues.
This (as far as I know) is the main reason many pools in many, many places (not just Europe) will no longer allow swimming shorts but only the skimpy speedo-style swimwear (hoping that people wouldn't go around town wearing those).
However policies are really specific to each pool, so your best bet is to check the rules they publish (usually available on their respective websites).