I don't really understand why anybody would _not_ use a seatbelt in general.

Sadly I have seen a number of people use "alarm silencers" basically just an end cap to fool the automated system that the seatbelt has been engaged. They even have some cute designs with Micky mouse heads for example.

Even people that have grown up with seatbelt alarms. The common explanations I've seen is that it "messes up my suite" or "feels uncomfortable".