One of our local airfields is a small D class, towered during the day, probably kept running at this status mostly because of historical/charity reasons. It gets 2 or 3 commercial flights a day and a moderate amount of General Aviation local traffic.
We have just one Fixed Base Operator (FBO) there.
My instrument instructor recently had a payment misunderstanding with the FBO over some hangar time. He paid what they asked, but wasn’t happy about it. Because his displeasure was expressed (and probably because of some past disagreements as well) the FBO's owner informed the instructor that he wasn’t welcome there anymore and neither were any of his students.
There’s always two sides to every story and this doesn’t inconvenience me right now, so I’m not looking for any advice on the actual situation itself.
What this situation made me curious about though, is what rules (if any) govern FBOs? Are they just “normal” businesses? They have an interesting relationship where they have a quasi granted monopoly to serve the public. I assume that if I tried to open an FBO, that I would be influenced, at least partially, by both FAA and the local port authority.