Using people to pick up trash and throw them properly is the solution that has been used for centuries. Crows are paid peanuts (literally) for bringing back trash. They are employees.

And I am sure that if you were to offer people a dollar as a reward each time they bring back a trash to a trashcan, the parks would be clean.

In Berlin glass bottles are reused and there is a reward for bringing them back to specific bins. I have seen homeless people looking for trash and filling carts of these.