But do people really commonly refuse to move out of somebody else's seat? I fly a couple times every month, and while I have found people sitting in my assigned seat from time to time, I have never had anybody actually refuse to move once I politely point this out and show them my ticket stub.
Is this really a thing?
It's kind of astonishing to experience, to be honest. To witness someone committing to a thought process that is completely unfathomable to you.
I did relent because the flight attendant asked me nicely if I mind just taking the middle seat. It was the first time I got a window seat that wasn't over the wing!
I would guess that it is probably gradual adaptation to flight attendants not wanting to properly step in and deal with enforcing the rules, thereby empowering the most obnoxious/rude/sociopathic passenger to "win".
Now I kind of hope it happens to me sometime... sounds like a vaguely interesting problem to deal with.
[1]: the best kind of data!!