They have no jurisdiction on private property. You don't even need a license to drive on private property. Their [already thin] claim to have the jurisdiction to require you to have a license, register your vehicle, etc., hangs upon the idea that the roads are "theirs".
Sadly, another appellate court issue, or at the very least reason to get an attorney or otherwise research the actual traffic statutes. Some traffic statutes apply to private property that is open to entry and exit by traffic on the public roads. Others don’t. Where I am here, there is a sign at the exit to a nearby post office parking lot urging people to buckle their seat belts. Maybe Federal property is an exception to state and local rule.
no, people have got tickets riding their lawn mowers drunk on their front lawns.
The reason is they say if they weren’t there you could potentially go onto the road.