Varies by state and age? My very red state does not allow a group of 40, full stop. The largest group allowed is for 3-year-olds, with a 1:15 adult:child ratio. For younger children, the ratios and group sizes are smaller.

I was off on the 4-5 though. Ratio for < 1 yo is 1:6.

Anyway, this is all to the point that it's nothing like the 1-2 in in-home care. There's a reason nannies are associated with richer people.

Given the cost of out of home childcare, three kids more than pays for a nanny. Even two can.

Not exactly a “rich” thing, just a matter of “scale” (in YC terms).