live in maid service has been tightly regulated by HK gov't for decades. There's minimum wage. Requirement for stipends. Proof of income and assets. etc. Workers are usually from southeast Asia from lower cost of living.

I lived in HK in the 80s and while we didn't have a maid, our 3BR apt had a separate maid room by the kitchen w/ own bathroom. It wasn't uncommon to see that.