It does happen in some bars, as the OP found out. But not in every gay bar, and I'd think it's the exception rather than the rule.
I've seen stuff in my day, not so much out in the open though. Did see oral/anal at a bar in New Orleans. Mardi Gras - and it was a stop when I was on a gay cruise. One guy was getting fucked right out in the open, huge crowd around. Saw him the next morning on the ship at breakfast, and I was thinking "I know what you did last night..."
OP - this does not occur at most gay bars, so you may never encounter it again.