>Again, I'm convinced that for a large number of people this is not about selfishness and self interest but about plain principles.

Those "plain principles" are usually that somebody else should pay.

Uh-huh.
If they were advocating fairness, it would be the same rate for all, not a higher rate for others.

I think they misunderstand the Robin Hood stories.
Robin Hood is often (incorrectly) said to:
"Steal from the rich to give to the poor"

In fact, the stories are about fighting against an overly-greedy tax collector so the people could keep (or steal back) what they had earned.