The data shows that the biggest factor is the increase in rental rates relative to income. Drugs and mental health problems are more of symptoms of poverty and a terrible health care system.
If you want to put it in the simplest terms, the increase in homelessness is caused by wealth and income disparity.
Yup. And there will be continued efforts to completely ignore every bit of data that definitively shows the ruling ideology to be the cause of the problems because that would mean rich people gaining wealth at a slower pace.
Zoning laws have gone far beyond their useful purview and are now gerrymandered to protect the property values of wealthy people.
This is the problem, not the government itself. Wealthy, greedy people have subverted the system to artificially restrict supply. There really isn't a supply problem as there are far more extant homes than human beings. The supply, however, is also artificially constrained by investors keeping empty homes off of the market.
Lack of affordable housing certainly seems like a contributing factor. Drug addiction and mental illness complicates the problem though. Virtually no one will rent to, or rent to for long, someone living that life without treatment.