17,000 people need to be evacuated from Houston.
Son of Roy

This question was addressed by authorities. The decision was made to shelter in place as there could have been more deaths with people out on the road snarled in traffic jams. Besides, once you have hundreds of thousands of people on the move, what do you do with them all? Considering this is an unprecedented rain event for the Lower 48, I would say the authorities have done a pretty good job so far.