It's madness. I understand some of it is a flaw by design in federal states (Germany has some disparity between how strict each lander is) but in the US the response has been all over the place while domestic air travel was, AFAIK, mostly going on as normal though I'm sure passenger volume reduced of its own volition.
I don't think it's even constitutional to restrict domestic travel.
The Feds could surely suggest to airlines and train operators that it would be appreciated if they lowered the number of flights/trains/bus, maybe that they should only sell so many tickets that social distancing would be possible for passengers... Especially if they want that sweet public bailout money.
And didn't Trump suggest that roadblocks be made out of NY and parts of CT ? Maybe it's the States that decide this but I also thought I heard that they could force interstate travellers into a quarantine ?
I know this will give Benji seizures but while it's kind of worrying how all Western democracies basically just flipped in a couple of weeks to de facto state of emergency where freedom to travel and congregate was curtailed overnight (and the French government tried to slip in some skeevy changes to paid leave and a couple of others labor code changes via decree), there's sort of a tacit agreement with citizens that it is exceptional and temporary (at least so far...) even though I'm sure a lot of the measures could fall in a gray area and be challenged in courts.