You're closer to a solution now.
Yes, there are other possibilities. By nature those are more bureaucratic and jittery. Maybe they are closer to a solution now, but if that's the case, it's because it easier to make that law more relaxed than strict.
Taxpayer pays x to government which pays workers to clean.
Taxpayer pays x-y to government which pays x-y to government workers who need to go out and negotiate without private businesses and inspect to see if they are doing their job and then punish them if they are not and then deal with disputes. And it is very possible for y>x.
The idea that a government can maintain all the surfaces of a large city in a pleasant situation is completely unrealistic. It can at most decentralize to to smaller bodies (and get a huge variance of outcomes, what is quite an ok solution too), but São Paulo doesn't have those bodies and is organized in a way that makes them almost impossible to create.
Yeah, maybe the best policy for the city is pushing governance into smaller bodies. But if your goal is to make the city visually pleasant, that's the solution that will take decades instead of years from the alternatives.
Not really. The biggest corruption, waste of money and worst outcomes are when private and public sector intersect. Pure public (like healthcare systems outside US) or private (like food distribution) segments work best.
