And, part of most driveways contist of several feet (or more) of easement as well, which isn't going to be considered "private property" in such cases. If any member of the public could pull into that driveway to, for example, dig out and read directions, check a map, answer their cell phone, turn around because they missed their street, or other lawful purpopse, then there's no reason why law enforcement couldn't make use of the area for periods of time as well, particularly if that presence doesn't interfere with the owner's ingress or egress. (Note that even the lowest forms of trepass generally require there to be either notice by the owner, OR criminal intent to enter and remain on the property. Just as sitting in a random driveway to check a map or make a phone call won't generally be seen as "remaining", so to is law enforcement not going to be subject to an unlawful remaining for sitting there and running radar for a while.)

