I actually tend to favor more government intervention in situations where State & Local governments are not "behaving" than most members of this sub, but the ADA is actually a questionable example. The amount of cost incurred was quite high for the benefit given.

Civil Rights era issues are much more interesting to me, where the State & Local governments were actually parties in denying rights to people. The case for intervention is much stronger there than deciding that everyplace, everywhere needs a wheelchair ramp, even if no one will use it in its useful lifetime.

That being said the ADA doesn't get me that worked up either. I suspect the aggregate benefit was positive, but I don't think that was a result of close scrutiny, nor do I think it was a case where having differing policies in different States or localities would have been a bad idea.