Apartment walls are thin and leak. Never smelled your neighbors cooking or smoking?
Apartments have common areas.Never walked down a shared hallway or staircase or used an elevator in an apartment building?
People move. So someone moving into an apartment after someone who’s had a dog or cat is going to have to deal with the leftover dander. You can’t get it all, even with a good cleaning and ripping out carpet. It’s similar to when a non smoker moves into a unit previously occupied by a smoker.
Look — I’m fine with allowing pets in apartment complexes — I just don’t think it should be mandatory. Perhaps this legislation could compromise by saying something like “when there are over X number of units, Y percentage of units must allow pets of up to Z size and number.” That way the pet and non pet people apartments can be separated from each other.
I have lived my entire adult life in apartments. Aside from a few foolish times I was in a complex, I’ve spent the rest in buildings put up before 1930. I’ve never experienced the issues you mention. Older construction is better because it was overbuilt. Today things are built as closely to standard as possible to cost save.