The homeless in the US that you see living in tents and underpasses etc. are the mentally ill, and the chronically drug addicted or a combination of both. Those people aren't going to be helped by building new housing. They need treatment and probably will need to be forced into assisted living accommodations. We definitely need to build more housing in most cities, but most of the governments in these areas make it difficult to do so. Once the baby boomers start dying off, we should see more housing hitting the market...