I definitely still see honor system pay boxes in the USA. Maybe not in big cities, but outside of them.

Disc golf courses, fire wood piles, that day’s chicken eggs in a wooden box on the side of the road.

I came to this country as an immigrant and one of the first memories I have was walking to the gas station to get the Sunday paper for my host father. I remember opening up the door and seeing tens of Sunday papers and was taken aback thinking how can this be, wouldn't someone just put in a quarter and take ALL of the Sunday papers home with her/him. In today's society (and especially if we are talking Princeton-like places) I do not believe honor-anything "works" anymore and am wondering just how small a place needs to be where this exists today...

just as a small recent-ish example, I live in a white-collar affluent area and this Halloween we took our daughter to her friend's neighborhood but left a dish full of candy outside with a sign to take a couple. we have a camera outside and the very first "group" of 3 kids (with two adults) that came took all of the candy that was there...