That's obviously you working backwards from your opinions on America. Nobody advertises it here nor have they in a generation or two. It's an assumed default to the point that anti circumcision activists often have to argue with partners and sometimes circumcision is done without parental consent.

Here's Wikipedia on the history of the practice

But fundamentally, this comes from the late 19th and early 20th century where it was seen as an attempt to reduce masturbation and disease. There's no reason to believe that the doctors recommending it at the time didn't sincerely believe it to be for the best, it was just a time in which medical science was a bit bonkers.