The number one thing is moving risky things outdoors. That could have helped churches, gyms, bars, and restaurants. Schools, too.
For schools, why should a teacher have been willing to teach in person if the rest of the public isn’t willing to skip the restaurants or wear a mask? You were asking the teacher to accept an elevated risk, while you do absolutely nothing to help.
Yes, the risk to a teacher in a well ventilated room of masked kids is low. Now think about what happens as you relax those assumptions. The risk stops being low.
Suppose kids are refusing to wear masks. Is the teacher allowed to kick kids out for not wearing masks? Unless it is private school, probably not. So assume the kids, like their parents, skip masks.
The AAP assumed ventilation. Will anyone actually upgrade the ventilation system in each classroom? Don’t be silly. They can’t even keep the water faucets working. At most, they’ll send out an email asking teachers to open a window.
So, if you require teachers to teach in a well ventilated room of masked kids, you also require teachers to teach in poorly ventilated rooms of unmasked kids. It is no longer a low risk, but it is what will happen.
This is why I supported outdoor school, and school with each teacher teaching a single cohort. School is important, and moving class outside seemed the simplest way to make it safe.