It sounds like you're aware that, according to official statistics, homelessness is higher per capita in Australia than in California or the US as a whole. I'm open to the idea that this might be due to definitional or measurement problems, but you've gotta explain what those problems are, not just assert that they must exist.
The obvious alternative explanation is that Americans might simply be less tolerant of measures to decrease the visibility of homeless.
sorry, but HN isn't a great medium for long technical posts :)
The basic issue is that Australia naive measurements and numbers carry a three tier definition of homelessness: at the lowest level you have what we call "sleeping rough" which is probably the concept closest to what most people and Americans think of as "homeless". But the Australian definition also includes the likes of insecure accommodation and inappropriate accommodation: couch surfers, people living in accommodation with inadequate living conditions, people sleeping in their cars, in socially provisioned homeless accommodation and emergency/crisis accommodation (domestic violence, youth, men and aged issues were the traditional breakdown of most services in my day).
To compare between the two nations from official sources you have to bring them back onto a somewhat comparable basis.
That makes sense. I'm gonna have to dig into the exact definitions at some point, but I agree HN comments aren't a great place to really get into that.
there's also a couple of sources and differences: the main one commonly quoted is the ABS source, derived from the census taken every 5 years, and with specific practices implemented to try to accurately enumerate homeless populations. thankfully there doesn't seem to be enough variance for the relative infrequency to be an issue, but the other quirk is that census is done in winter, and contrary to some popular impressions, homeless populations can be highly mobile and show seasonal effects.
Another source include homeless service provisions, but last time I looked at those they didn't always tend to be on a individual natural person basis.
lastly, homeless service provision, with a few caveats, is one of the only things that might locally and empirically show behaviours of what economists call a "giffen good". And, somewhat paradoxically, provision of homeless services can, to a point, increase the percieved systemic demand for homeless services. increased supply can also create more (real and percieved) demand. the relationship these complexities have with trying to measure homelessness is tricky to say the least...
The obvious alternative explanation is that Americans might simply be less tolerant of measures to decrease the visibility of homeless.