I'v done a lot of flying as SLF recently and I've noticed this too. At one point on a 8 hour flight across the pond we did have some major turbulence, but the seatbelt sign was left on for the remainder of the flight, about 5 hours.. After a sleep I woke up and wanted to use the toilet, in my sleepy state and on seeing at least 4 pax lining up for the restroom I didn't notice the seatbelt sign was on until I was half war through econemy class.
A lot of passengers don't care and as do any of the CC.