Every state has different tuition rates for out-of-state students.
It's because the families of non-residents don't pay the state taxes that subsidize the higher education system.
There are a lot of theories about why states give instate rates. At the same time were you aware that Texas universities are authorized to take the rates away if you end up taking too long to graduate OR if your grades sink.
They punish slower students with higher rates. Now what the devil theory is that one?