San Francisco Behavior Pattern? "Helpful" Shout Outs

I saw this happen twice today. We were on the public transit in San Francisco. The first time we were on the N streetcar, in the underground, and were just short of the Embarcadero station. The car had stopped, but the doors had not opened. While we were there, my wife asks me, and one of the people standing by the door, if we were at the stop and if the doors were going to open. The woman turned around and shrugged her shoulders.
Just then, there is this woman's voice nearby that says "We aren't at the stop yet."
I turn to see who spoke. Nobody is looking in any direction. Nobody is looking toward myself or my wife. Everybody is looking down at their newspapers, magazines, cell phones, etc.

Later, we were on the F line (different street car, picks up at the Embaracadero station) and someone starts to try to get off at the back door. He shouts to the driver "Back door!". A few seconds later, someone randomly says "Step on the step" (the doors open automatically when someone steps on the step). Again, nobody is looking at the guy. The guy doesn't turn to acknowledge anybody. Everyone is looking at their own business, books, phones, feet, whatever.

I have never observed this before. Every time I have seen anybody say something to anybody else there is always some sort of acknowledgement of the conversation. A nod. Eye contact. But this was almost like people talking to themselves, which was really weird, because they were technically offering help and instruction, but without directly looking at the person. It was hard to tell if this was "Hey, let me help you.." conversation, or if this was, "Oh geeze, you idiot, can you just get on with it...?" conversation - I try to avoid interpreting behavior, especially when it is so usuual to me.

So, is this a San Francisco thing? A big city thing? I don't know if ANYBODY reads these blog postings, but if anybody from the SF area, or from somewhere this behavior is common reads this, let me know.