Well, that's always been the case with Skid Row, though it might be debatable which came first -- the homeless encampments or the aid agencies. And for that matter, there were Hoovervilles in the Great Depression. In any city in America, there are transients milling around the shelters, which is why there's so much NIMBYism over developing new shelters.

But what's going on in California probably has more to do with the fact that LA and San Francisco tend to be very tolerant of the homeless encampments and provide generous aid, thus inducing demand. The homeless population is soaring across America for various reasons, but California is a desirable place to be homeless: better aid, better climate, softer police, etc.

Maybe California's big cities really are more humane and generous, but at this point it's to the detriment of livability in those places.