I just returned to Tucson after 3 years away, and I notice more homeless people. My theory is simply quantity--there are more people so even if the percentage of homeless is, say, 1%, it's 1% of a much bigger number. There are only so many public spaces to go, and only so many "livable" cities due to weather and services. And, of course, the % of homeless is going up because once you lose your place, e.g. Covid, it's hard to get back to one. We need universal basic income in a big way.