JUUD, I hear what you say but their "buy your own seatbelt" is a misleading advice. I cannot buy my own seatbelt and use it on board! Extension seatbelts have to comply with strict regulations,they are part of the a/c SEP equipment and are all the same, the pax might buy the wrong thing, not strong enough etc etc I could go on forever.
Plus, not enough seat belts (whether extension or normal seat belt -it's not unusual for naughty ppl to steal them occasionally
) is a no-go.
No seatbelt, no take off! A missing belt is just not acceptable!! I was in the position to have to offload two couples with their babies on a return sector from TLS as we were lacking 2 extension seatbelts (NOT our fault, that plane type always has the same number, it was the airline's who had accepted way too many infants for that flight!)
As for not disturbing people when they sleep and the seatbelt goes off, I am totally against it. I always "disturb" them as their safety is my job and I cannot foresee how the turbulence is going to affect us all. If the captain makes that decision for us we (including sleeping pax) should respect it.
I do not agree with this practice but I accept that in some circumstances some FAs turn a blind eye.
However there's a substantial difference between doing it occasionally and not advertising it and actually writing it black on white on your own in-flight magazine!!!!