If you buy land where the only access is through another person's private property, that is your own fault. The purchaser has a responsibility to do their own due diligence.
Similarly, easements don't go away when they change buyers. For example, if you own a landlocked property, and you have an easement with your neighbor that allows you to drive across his property on his private road to reach yours, and then the neighbor sells his property, you can still use that road - the new owner cannot say "tough luck."