"Additional states (including Arizona, Texas, South Dakota and Oregon) have such laws just for motorists" implies that others do not, correct?
What we're talking about is more specific than that, and other statutes are implicated.
If you were operating a vehicle and cop pulls up next you and casually asks about your day, then you don't have to identify, because that's a consensual encounter. If he suggests that you rolled through the stop, even if you didn't, then you're subject to things like implied consent that are attached to vehicle operation.