People who are courteous are eager to please, just like the people willing to kill on someone else’s say so...
I think you have a point, but I believe it is contextual.
If you put someone in a situation which plausibly seems to comply with social norms, then -- yes, they might go along if it seems to them to be the 'appropriate' thing to do.
The volunteers in the program had little external reference -- just the 'professor' in the lab coat and a person who seemed to be a willing partner. They were on their own, and it seemed appropriate to shock a person who was, in all reality, anonymous.
The people on the subway who gave up their seats likely (yes, I know -- assumptions are what they are) had little external reference for their decision to give up their seat. I would have been interested to know if the researcher approached individuals, members of a group, people of approximately the same social level, on a crowded train (one would suppose) or a near-empty one.
But the connection between courtesy and compliance? I'm not so sure. I've met some very courteous people who were extremely independent. And some very rude people who would go along with whatever was asked, but b1tch about it the entire time.