In Malaysia we had this - they're often brought in from Indonesia, especially the places which are destitute. Recently Indonesia has been rising in wealth (though recent politics have fucked that up). And Malaysia has become more of a high income country, meaning everyone lives in condominiums without spare rooms instead of suburban houses. I don't think this is affordable in HK or SG.

It was also a culture shock when I went to Australia and found everyone cleaning up after themselves. Apparently it doesn't work as well in richer countries due to higher cost of living/minimum wage.