It is obvious that the US education system is a mess. Ideas for helpful reform?

The flaw in your thesis is that the US doesn't have an 'educational system'. Every state has its own system and every locally elected school board has influence as to what is taught, how its taught and who is hired. Contrary to popular belief teachers and teacher unions have almost zero input as to what is taught or how its taught. Teachers are 'employees', they're not in anyway management.

Some states and districts do excellent work, and some, even in the same city don't do very well at all. School funds come mostly from local property taxes. Some states toss in state funds and sometimes the federal government throws in some money, but the 'rich districts' still have the advantage.

Most countries do have an educational 'system' that includes the entire country. South Korea and Finland seem to have the best outcomes. Even China does better than we do along with India. ALL schools are equal in regard to money and there is a single learning plan for all schools and students. Teachers are regarded with respect... in the US? Not so much.

A helpful reform would be to stop trying to force the privatization of education on the public schools, make funding a priority and admit that our balkanized non system has had its day. Some student populations need more of everything to bring out a better result. At this point those the most in need get less of everything.