Ah, most of the cyclists YOU know.
Most of the cyclists I know don't , so like your estimations, doesn't mean a thing. I never said anything about cyclists looking behind them! On a couple of occasions a cyclist has come out of nowhere, up the inside as I'm about to make a left turn. Helmet, hi-viz, camera, all the gear and no idea!
I always give cyclists plenty of room when passing, but there's just too many dicks that use cycles with no regard to their own or anybody else's safety. At the end of the day, if cyclists had a bit more consideration at junctions we wouldn't need to be installing mirrors on traffic signals would we?