That is the Texas Law (Created by Little Bush).
UT at Austin does not want to do it but the Texas Congress (proposed by Little Bush's friends) passed that law.
Right now, there was a little changes. 10% is not guranteed now to be admitted to UT. You need probably 8%. The put a cap on how many top 10% students can be admitted to UT and Texas A&M Univ.
Xiong