How long do they usually put madames in prison for in the US? - madames for girls who are underage (in some states but not others). So a worse situation than being a pimp for adult prostitutes, but not as bad as a pimp for paedophiles (using the legal definition).
Being a madame is not a crime in Nevada, where the age of consent is 16. So I suppose Americans aren't exercised by 16+ prostitution so much, as they go to Nevada to entertain themselves in various ways without expressing their moral outrage. Indeed, 16 is the most common age of consent in the US. It's exploiting girls under that age that is the really dark thing.
That is what Ghislaine Maxwell has been found guilty of as part of her trial, I think. It's the girl who was 14 that will (and ought to) define the sentence. In particular, she owed her protection.
[I still find the notion of a large network of famous men as part of a network of illegal underage sex parties preposterous. More Eyes Wide Shut than reality. Whatever Maxwell did, I think she did it for Epstein.]