Perhaps. However, based on my experience S. African appear to me as level headed and reasoned people, even when they talk about apartheid. I had a conversation with a cab driver in Cape Town, as he was showing me different vestiges of the apartheid era 9separate this separate that) - and what stuck me was his matter of fact narration even when he made it clear what those vestiges meant to him (he was black, obviously). I was quite impressed, because when I tried imagine myself in his shoes, the bitching and ranting would probably never end. That was also my impression of other S. African I met - soft spoken but matter of fact. A sharp contrast with the the garbage that many US-ers put on the internet and public sphere.
I do not hear many boomboxes, but that I guess is the matter when one goes (I did not go to the townships). But I did not see many boomboxes in Nairobi either and I did go the slums there.
As far as Europe is concerned, the thing that strikes most US visitors is how quiet they are comparing to the US cities - this is not just my observations, others observed that as well. There was even a New Yorker cartoon: parent telling to their kid 'be quiet, we are in Europe."
BTW noise making is an act of MALE passive aggression - you do not see many females revving their bike, blasting their boomoboxes etc.
Wojtek