You can't fine the homeless, no revenue for the city.
That's actually very true, which is why the city "can't do anything".. couldn't do anything. There is a case that was just ruled on today by the Supreme court that claims fining the homeless for camping on public land is "cruel and unusual punishment" if they have no alternative. Meaning the shelters are full.
That case was shot down and gave the OK for the city to enforce homeless rules again.