common people are definitely involved in your infrastructure is designed.

from electing officials who approve projects to whoever is in the design team.

plus, add the cirbcut effect, wherein accomodation for disabilities ends up being helpful and convenient to everyone.

and you are wrong about an absolutist statement of "they rather not be disabled". especially considering that in many aspects, it is society that disables them, and that can be fixed. but because of lack of representation, it is ignored instead.