In principle the solution is trivial. You raise the bar for becoming a teacher (supply will grow as well if salaries are much higher and there are these benefits like respect and autonomy). And then if some bad teachers do get in, the institution uses personalized oversight (in the form of "good" teachers observing and critiquing "bad" ones), and any problem teachers are given a smaller load with additional training. In other words, you invest to make all the teachers good.

The question is whether public schools have the funding to do this, and that's a more political question.

Teachers are not all organized like that. Just the ones for public schools.