Letter of Demand re: easement

Seems like a good time to bring up the concept of “corner crossing”. It’s a bit of this thread, but on a much larger scale, and also a LOTTTT lesser impact. We are talking about walking over the corner of a property vs driving over the entire property. How can a private property owner restrict access to public land when you may not even touch that private property? I know it’s not apples to apples, but it should show you the issues with private land rights and how they might have a bit of overreach.