Per every state law, it's required that every vehicle parked or driven on public roadways displays registration (ie. a license plate), except per certain exemptions (police, military vehicles, etc).
It is not legally required to display registration information while the vehicle is driven or parked on private property, even if the vehicle is visible from a public roadway.
Given that, is there any legal obligation to display a license plate while a vehicle is parked in the parking lot of a private business? Would there be any possible repercussions if someone, for instance, removed their license plate and put it in their trunk when they parked at the local Walmart?