Except in a few liberal-infested states like California, no license or any other form of credential is required to own a vehicle if that vehicle will not be used on public roads. Anyone--regardless of age or criminal history--is allowed to purchase or own a vehicle, and anyone may operate vehicles on private property with the permission of the propert owner (it used to be, and probably still is, common for children twelve and under to drive cars around on farms). Although in most cases the operation of a vehicle on public roads will require both the vehicle and owner to have government-issued credentials, vehicles may be transported (not under their own power) anywhere without any government credentials. When government credentials are given in any state to operate vehicles, the credentials are honored in all 50 states.
Somehow treating guns like cars doesn't seem so favorable to liberals, does it?
BTW, another difference between firearms and cars is that it is very common for people to leave their vehicles unattended in areas which are accessible to the general public (indeed, vehicles and bicycles are probably the only type of item so treated). Registration can be useful for contacting the owners of vehicles (or bicycles) which have been left somewhere they shouldn't be. Although registration could theoretically serve such a function with firearms, as noted before most people don't leave firearms unattended in areas open to the general public.