4.5? At a US daycare those kids will be in a group of 20-40, with one or two adults supervising.

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.

In California, at least, those numbers wouldn't be acceptable.

My daughter's at an in-home daycare with IIRC five or six other kids. There are two adults there full-time, sometimes three.

Two adults supervising 20-40 daycare-aged kids is simply not feasible.

Depends on the state and child age. California is on the stricter end of legally mandated ratios:

0-18 months: 1:3

18 months to 3 years: 1:4

3-5 years: 1:5

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.