If somebody from another state moves to Mexico and lives there for -- I think -- a year they get in-state tuition.
If someone from Mexico sneaks over the border he doesn't.
However, if someone from Mexico sneaks over the border with his kids and manages to enroll them into a Texas public school -- something which, btw, is protected by the SCOTUS -- and the kids spend at least three years in the school system and they graduate from a Texas high school they will get the in-state tuition.
Thanks for reiterating the fact that in Texas, Americans in 45 other states are second class citizens to illegals.