If you read the classic “How the other half lives” – it appears that 100 years ago there were a group of non-Jewish (primarily Irish) women who sole parnassah was working as domestics on Saturday to fill in for the Jewish domestics who didn’t work Shabbos, but worked the other six days. But that was over a century ago.
But wages and opportunities went up, and most Jews (and Irish) in America went into lines of work that pay much better. At the same time the minimum wage priced most domestics out of a job, and people switched to using tech rather than hiring domestics.