Mainly based off my experience growing up as a migrant family in nyc and talking to other people along with their experiences. Everyone is different so I doubt my explanation fits the norm but it’s what I’ve seen the most growing up.

they usually share them across different families or friends and pay for it together

You can buy a box of those sets from Costco or bjs for only a few dollars, sell each at 2 a piece and there’s a profit