I don't see why this couldn't be done on a smaller (state or county) level instead. If someone starts offering an attractive starting salary and that leads to b

I don't see why this couldn't be done on a smaller (state or county) level instead. If someone starts offering an attractive starting salary and that leads to better educational outcomes you would expect others to follow (at least make it easy to campaign on it). Edit: And obviously adjust the salary to match local conditions as you point out.