This happens all the time at ball games. Oh, I don’t mean Barbara Streisand is sitting in you seat when you get there in the third inning, but someone else usually is.
Yes, it happens at ball games. But the fans don’t think they are royalty and entitled to your seat. When you show up, they move without incident. Your name was not on the seat with a reserved sign. Streisand saw reserved with the name and sat there anyway.