I agree there are other distinctions that could be made here, but I think you're dodging my point. The question is about the subjectivity probability of the players meeting again. For the tit-for-tat strategy to work, the players must expect that they'll probably meet again, even if they don't know when (so their betrayal could be avenged). In real interactions in big cities, that probability decreases. The norm is for strangers to come and go, the exception being interactions with your family and coworkers, in which cooperation comes to the fore. Strangers get along because of civility, which is more superficial than heartfelt cooperation.

Anyway, thanks for bringing those kinds of prisoner's dilemmas to my attention. I've written up my response as an article, and it will appear in a week or two.