Please, do not get the issues confused between what we pay our teachers and what we pay head football coaches.
The state regulates the base salaries of teachers - including athletic coaches. Texas is fifth from the bottom because the state of Texas wants it to be that way. That is a battle to be fought in the Legislature and will not be won until the current Tom Craddick-Kent Grusendorf anti-education leadership is removed!
Football coaches are supplemented on a local, district-by-district, basis. That is a school board decision, in the same way that superintendents get paid more than $225,000 a year (such as Plano ISD) -- FAR higher than the pay scale just 10 years ago.
As I said, don't confuse the two issues since each has a different battleground.
Of course, in Collin County, since the GOP controls EVERYTHING, including city and school government, there is a tie that binds.