Yeah, and we don't know the reasoning behind either decision. I can come up with maybe a hundred different parameters that could be relevant or not.
At this point we can trust authorities to have a reasonable approach to this and that they monitor the situation closely. Or we can assume they don't.
In the first case, we follow the action plan. In the latter we do what we can, best based on actions that worked elsewhere. Just complaining about how insufficient actions are in our eyes doesn't help.
Anyway, there plans for stuff like this government drawers everywhere. Ranging from school closures to plan keeping critical infrastructure up. Heritage from the cold war.
And even if the US federal government seems to screw up, states like New York and Washington seem to react rather decisively. And we shouldn't forget that things in China are calming down to an extent ad-hoc hospitals are closed down and medical supplies can be shipped to Italy.