Is it really that easy? I don't know. It seems a little more complex than just saying throw some stuff in a car and find a place a few hours away for a few days. I've not been in that situation, so I really don't know.
There are shades of gray in this. Some folks probably had no reason to stay. Some are probably part of the vital infrastructure, but maybe they have families that should bug out for a bit. And then you've folks in the middle somewhere in there.
When I was young, my father's mother was in the beginning stages of ALS where she was living with my aunt, about a 10-15 minute drive from us. She had a living space on the ground floor and with relatives and friends, someone could keep an eye on her throughout the day. Well, we had a tornado warning one day. Everybody is supposed to shelter in, right? My dad and a neighbor jumped in the car and raced over to my aunt's to get my help get my grandmother to the basement. Technically they shouldn't have been out and about, right? But they were. Some individual situations like these arise, and so what do you do?