The thing is, what you've described is a relatively rare act of rebelliousness. People know they are being obnoxious when they stick their butt out of a window and that's the fun of it (not that I have done it lately). Public cell phone use, on the other hand, is rampant and people feel justified in their invasive use of their phones because they get away with it. Even people who might feel mildly embarrassed about using a cell phone in certain situations still do it because very few people have the guts to say anything or to demonstrate disapproval in any way.
I once saw someone throw a butt out of a car window while it was stopped. I reached down, picked it up and threw it back in the car. Sure, sometimes calling people on stuff can get dangerous but I'm just seeing way too much wimpy detachment from society these days, with too many people just not wanting to get involved. The result of such detachment seems to be that society is becoming much less pleasant to be a part of.
