How is that inefficient? If anything preparing major cities to be ground zero for crisis makes sense. Major cities have way more people from way more places, so it makes sense they would be the ones hardest hit by famine/disease/terrorism/etc.
We got lucky. Covid19, while deadly, is not as deadly as it could be. If we'd run into Spanish Flu, we'd be in a world of hurt right now. The more deadly pathogens out there are just not to be met with half measures. If you're talking Spanish Flu, you don't want to be putting Dallas on lockdown, and still have who knows how many people on the road to Norman, or Tyler, or Nacogdoches. All because they left before the city of Dallas was able to close the city. The city of Dallas would not even have the ability to know where those people are, or where they are headed, or what planes they are on, or what cars they are in. There really are no other options here, if you want to ensure maximum survival, you must have the coordination be at the federal level.
Again, with something like covid19, it probably doesn't make much difference. Sloppiness is not going to kill 10 or 20 percent of your population in the case of covid19. So we can tolerate the kind of Keystone Kops thing we've got going on right now. But if something comes along like Spanish Flu? I'm sorry, but we shouldn't be pussy footing around with a bug like that.
and as I understood it the spanish flu was rough but mostly it was so deadly because there were no antibiotics to treat secondary infections. And don't forget about lack of respirators.
If you take the original example, how would the state of Texas know where the kids who drove to Norman, OK are? They would need to, at a minimum, ask the state of Oklahoma. You scale that up and it's obvious that there has to be some mechanism for public health and law enforcement to act across state lines. That mechanism is obviously best implemented at the Federal level.
The government of Alabama can't be diddling about trying to find out who to call in Minnesota when they realize one of their residents left Birmingham just before a lockdown headed for Minnesota. Even worse, if the person was in a car, they'd have to check with every possible state, along every possible route to Minnesota. That's incredibly inefficient. We need Federal control of that stuff.