That’s because the Texas electorate is a little more white than the overall population, and whites in Texas routinely vote 70+% for the GOP. That is why they dominate the state...for now. Eventually mass immigration will break the GOP hold on Texas, as the white share of the electorate falls below the point where winning 70% of them (plus the usual showing with non-whites) guarantees victory.
Northerners and COW state whites don’t get it that we vote GOP despite our large minority populations because whites in the south mostly think alike from South Carolina to Texas
70-90% voting bloc
It’s Yankee whites that are the balance of power for Dems