Having not read the specific wording of the law I am curious, couldn't an employer just fulfill their legal obligation by saying the salary range is 1 to 300k dollars?

No, because it has to be true. All companies have their own scales, and they would probably get sued for not accurately disclosing those. There are also exceptions, which would go outside of the range and invite scrutiny/lawsuits as soon as a minority discovers one single white/Indian male whose salary exceeds the stated target range for "senior engineer".

It's one thing for employers to voluntarily provide a good faith range, which some will, but another when they expose themselves to a gender discrimination lawsuit by being wrong.

Also, everybody is going to insist on max(range).

This law seems to create a lot of legal landmines that I don't think will be beneficial. High earners can volunteer their salary anyway.

Could you elaborate?