I've been thinking about this, since returning from a residential last Friday.
Three parents thanked me.
I'm not expecting all out gratitude, but I was quite taken aback by our return in general. They all stood in the path to the main school entrance, two parents and a childminder helped us get the luggage off the coach while the rest watched, and nobody moved aside without being asked.
It's a very upper middle class school - wondering if that means the parents are much more 'entitled' feeling than others?