From your link:
"at one-eighth of the standard cost of development...Each bedroom unit has its own bathroom and shower to allow for isolation during the pandemic". So there are special pandemic isolation considerations factored in, which surely increases costs. That doesn't sound terrible if real shelter is being provided.
Do we think that California can just ship homeless people off somewhere else that won't then try to ship them back? Or do we think that the cost of building new infrastructure for them all in the middle of nowhere will be lower than the cost of building housing in already established infrastructure? I mean, it's obviously not as cheap as dumping them in the ocean, but that's not our target standard.
Between your link and the other person:
300 people sounds very different than "them all".