In absolute dollar values, they're definitely up there. However, salaries tend to be higher overall in the US because we have fewer social benefits. Relative to similarly-educated workers in other fields, American teachers are underpaid compared to other first-world countries:
Just how underpaid are American teachers? Dick Startz shows that teacher salaries are not only low compared to other similarly educated American workers, but also much lower relatively than those of teachers in other industrialized nations. Increasing teacher salaries would not solve all issues...
www.brookings.edu
And that's before accounting for the workload.
That's an overly broad generalization - there are good public schools and inferior private schools. Regardless, I don't see how Trump's plan fixes the problem. Private schools tend to perform better because they can be selective about the students that they accept, and they generally have smaller class sizes, which gives teachers more time to work with students individually. Nothing that Trump has proposed addresses those issues as they relate to public schools - in fact, his plan will likely make the problem worse