It's not just single moms with their daughters, look at Kit Culkin, he auctioned every one of his kids off to the highest bidder. Hell I grew up around Hollywood, knew at least a dozen… young men… brought from the Midwest by producers, acting coaches, or directors.
One very famous director would have 5 or 6 'Bois' living with him at a time, they were all alegedy over 18, but some of them could pass for 14.