As someone who has spent much of his adult work life transporting and working with adults and children with special needs, mobility and otherwise, I really hope, Chris, that I am not seeing implicit in your posting a criticism of ADA, one of God's gifts to folks with mobility problems.
Around this neck of the woods, anyway, I have
never heard of any structure being torn down because of ADA requirements. With a little care, virtually all historic structures can be adapted to the needs of the mobility impaired with minimal impact. Heck, even the tourist railroad industry has figured out how to do that.
Mike