If the aviation world thinks the disability regulations cause some increase in costs, you should look at other means of transport.
The railways have found the cost of trains has been doubled, just by the disability provisions. Wider doors, toilets that take up space for 16 seats and have to be duplicated for each class. And also they cannot use on any new operation older but still serviceable trains well inside their lifespan, that were built just before the regulations were changed.
Urban transport is worse. Underground stations can cost 3 or 4 times as much as the designs of only say 20 years ago, with lift access needed to every point. It's for this reason that much of what could have been built doesn't get built any longer. Just too expensive to meet the regulations now. So everybody loses.
It would be more acceptable if it were done for genuine need rather than political correctness. Out by me the London Underground Jubilee Line has all of these modern provisions for disabled access, with the wheelchair symbol everywhere. I have never, ever, seen a wheelchair user on the train. And if you ride on it, you won't, either.