Its all about mutual respect for other road users. A lot people seem to possess it, some people don't.
It goes for ALL road users. No one group has the right to be on the roads.
Tractors don't by law have to pull over and let cars past them, however where i live thats exactly what they do.
Caravan users don't have to do that either but having followed many through the roads of wales and scotland thats exactly what a lot do.
Cyclists don't have to pull over to a single file on the road to make it easier for cars to overtake, but most do.