[dragonwriter]

> That sounds a lot like regulating cross-state commerce, which is traditionally the purview of the federal government.

Except for very specific things that are forbidden to the states in Art. I Sec. 10, or where Congress has specifically closed off state action in its own actions under the Interstate Commerce Clause, states retain the ability to regulate commerce in manners that impact interstate commerce so long as they do not discriminate against interestate commerce compared to in-state commerce in such regulations.