IAH-SAT is ~215 miles and will take at least 3.5 hours if you go the speed limit.

It's not even the time that is the bad part about IAH-SAT (an to a lesser extent IAH-AUS), traffic is very heavy on I-10 and very unpredictable. A single accident can close the highway for hours. If I am trying to catch a once-a-day flight there is no way I am taking a bus.

VCT I can kind of understand or Sugar Land Regional to IAH, but SAT or AUS doesn't really spark my interest. A train on the other hand, would.