And yet... haven't you noticed that supermarkets in posher areas are less likely to have the coin slot? (Asda and Tesco are two whose policy varies by location).

And in supermarkets with large car parks there are return stations all over the car park. Which means you still need to pay trolley herders...

I am not in America, I can't therefore share your observation. But it is not news that crime of all sorts is lower in "posher areas". Of course it is. What's the point you want to go for?

I think the posh bit is slightly incidental, I think it's shops that people [can] walk to.

Never played Sim City? Zonal planning is not incidental.