The housing isn't vacant because it's not occupied. It's vacant because the owners have their primary residence elsewhere. Or have several homes. London has neighborhoods where full time residency runs around 30% as well, leading to "ghost towns" - supposedly much of that is Russian or eastern euro money being kept outside of their home countries less as an investment than a value store. I have a friend who is about to close on a condo in LA - all cash - and already owns homes in Asia and New York. She views them as investments but having paid cash she has no interest in renting them out.