If you wanted to add all that you could - I think that would be overkill personally, but there's nothing stopping you. But the question here isn't what ought to be added, but whether things should be *removed* because they're on private property, and the answer to that is no, barring the sensitive edge cases given in the wiki articles you have been sent. The data added here isn't functionally much of a different 'representation' than the countless satellite images that exist to be viewed freely online. You're right that nothing to the north has been mapped to this level of detail yet, but that's mostly just because nobody has gotten around to it yet. For a close example, the Martis Peak/Juniper Creek Ranch neighborhoods also have extensive private forest roads that are mostly all in OSM. The easement/access issues you describe I assure can be found in numerous other rural areas that are also in OSM. That is the purpose of the 'access' tag. If the roads are physically posted as 'no trespassing'/'private', then they ought to be tagged as such in OSM, which will render them as private roads on the tile map and prevent anyone from being routed over them with the navigational tools. But no map or online tool ever stopped anyone from ignoring posted signage and driving in places they obviously shouldn't, which has been a problem in this area long before OpenStreetMap has even existed and won't be stopped by deleting data.