Earlier quoted context omitted.
shame only works if there are consequences. if you're not calling them out then you are complicit. you are accepting that, and you need to live with it. if you want someone to respect your feelings then ultimately you will have to make them. for broke-ass hoodrats, for whom economic factors won't work, that means eventually going to Louis' ultima ratio -- e.g. calling this out may lead to a fistfight on a moving bus.
More to the point, we currently share a society with many people of a violent culture, which makes directly shaming them dangerous and unwise. This was not always the case. The death of shaming is largely related to the increased daily proximity to violent subcultures who do not fear consequences.
Disapproving glances on the subway when their music is too loud does not rise to that level, however.