I'm waiting to turn left at a permissive intersection. Asian female in
the oncoming traffic stream wants to turn right, but stops (with about
10 other cars trapped behind her) and waits for a bunch of us to make
out left turns in front of her.

Later on in the day, I'm waiting to pull out of a shopping center
driveway. I need to make a left turn shortly after getting out onto
the street, and nobody is behind me, so I am waiting for all three
lanes of cross traffic to clear. Mr. Courteous in a minivan comes
along in the middle lane and stops to let me go in front of him, but
the left lane is still blocked so I'm not ready to go yet. He sits and
waits, with a couple of cars stuck behind him, until he realizes I'm
not going to turn immediately, and then he finally proceeds after I
wave him on.

If I seem unappreciative of these peoples' "kindness," it's because I
am. These people may get an A grade for having their hearts in the
right place, but they get an F for not using their brains. Stick to
the rules of the road, and drive in a predictable manner - don't
surprise everyone by stopping suddenly out of "courtesy." Not only is
stopping decidedly DIScourteous to everyone stuck behind you, it
creates a dangerous situation where your moves are now somewhat
UNpredictable. And unpredictability is what causes "accidents."