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.
Bullshit. Most US states have strict staff ratio limits for properly licensed daycare facilities. The exact ratios vary by state but typically this is something like 1:4 for infants up to 1:14 for school-age children.