Because getting dark before the little kids did their trick or treating was too dangerous. By postponing the change until after Halloween, it became possible to get them into their costumes and take them out on their rounds before dark. Many places don’t take advantage of that and the little people are out on unlit streets in the dark still, but lot of cities do. Doesn’t really answer the question, because I don’t think it as ever on the equinox — who wants to lose an hour’s sleep mid-week? Unless, you work on weekends of course.
Beatniks – you’ll need to look them up if you aren’t familiar — called money “bread.”