I only know of a couple of what I think are 100% US manufactured bicycles. (When I suggested one to a fellow looking for an 'American bike' on this list a few years back, I got a profane reply!)
Other so-called US made bicycles are US frames assembled into rideable vehicles with imported parts. Often the value of the parts exceeds the value of the domestic content.
Are USA made bikes and accessories of better quality than China made?
Well, go down to your local Walmart, inspect a BCA bike and if you think so, buy one!