That vacancy rate is a bit deceptive unless you're clear what you're looking at, and why. Even when housing is conceptually "full," meaning that houses are occupied, or will be occupied very soon - there will still need to be some buffer between occupants. A house might be vacant for a few months while being sold, for example, or for a couple of weeks between tenants. But that's a different sort of vacancy than when a home is intentionally left vacant with no short-term intention of occupying it.
This is just like "full employment" is still maybe ~2% or so unemployment, because there are always a few people between jobs, but who will likely become employed very soon.
In the US, our 16M vacant homes are the former, "normal" kind. In China, the 65M are actually left vacant indefinitely with no expectation of anybody moving in soon. Not that you can't find some exceptions in both cases, but this is mostly the case.
This is just like "full employment" is still maybe ~2% or so unemployment, because there are always a few people between jobs, but who will likely become employed very soon.
In the US, our 16M vacant homes are the former, "normal" kind. In China, the 65M are actually left vacant indefinitely with no expectation of anybody moving in soon. Not that you can't find some exceptions in both cases, but this is mostly the case.