Average pay for a 5A or 6A High School Football Coach is $98,700.

"Football is to Texas what Religion is to a Priest" - Dallas Cowboys Coach Tom Landry

While the State of Texas remains unable to fund its public schools equitably, the Friday night lights burn brightly.  Average pay for a 5A or 6A High School Football Coach is $98,700.
While the funding for public high school coaches is supplemented by taxpayers and local donors, the inequity between teacher salaries, principals, and even school superintendent salaries with those of high school football coaches is remarkable.

In addition to salaries are stadiums such as Katy, Texas' high school Legacy football stadium which was built as a cost of $72 million, paid for by Katy taxpayers (Legacy Stadium).

For more on high school football coach salaries, see this link from the Texas Standard (Texas Standard).