I will admit that I'm slightly out of the loop since I haven't ridden with a pro in 10 years, but when I was part of a boarding facility you can bet that I wouldn't have stuck around where I wasn't appreciated. And there are a lot of trainers who *don't* treat you like an ATM. Heck, I work with a bunch of pros here and there who treat me like one of their own at horseshows despite the fact that they've never received a dollar from me.
Either way, pros are not indistinguishable from horseshows.....one doesn't need to ride with a BNT or even a T so go to a show. Perhaps part of the frustration folks have with shows really comes down to a lackluster relationship with their trainer(s)?