You guys need to expend just a little effort and research some of your claims rather than just try to force everyone to agree with your unfounded opinions.
Corner Crossing is Tresspassing and that includes crossing the airspace above the ground.
US Supreme Court:
United States v. Causby in 1946.
The court's decision, authored by Justice William O. Douglas...opined on what airspace landowners do and do not own. He wrote that
"if the landowner is to have full enjoyment of the land, he must have exclusive control of the immediate reaches of the enveloping atmosphere. Otherwise buildings could not be erected, trees could not be planted, and even fences could not be run". Thus, a landowner "owns at least as much of the space above the ground as he can occupy or use in connection with the land," and invasions of that airspace "are in the same category as invasions of the surface". There are many resources on the Internet that explain the rights of land owners to the airspace above their private property,
this link is one.
Most people wont make the effort to accurately cross at the exact corner and if they don't cross at the exact corner then they will physically step on private property in addition to violating the airspace above the private property, both of which are tresspassing. Additionally, while one person crossing one time at any point will cause very little damage (if any), hundreds of people crossing at that point over several years will cause an accumulation of small damages that eventually will be a major change on the land. Not everybody will be considerate of the land and try to cause as little damage as possible, in fact, most people wont care, they will just do what ever they need to do in order to satisfy their desire to get through the area.
In the end, under the law, it is tresspassing when you violate the private property rights of a land owner. While there have been no legal precedence setting cases of corner crossing, I'm sure that when one goes to court the land owners will win - if he can prove any damage to his property.
You have to separate your emotions and selfishness from the letter of the law because if you ever end up in court the law wont care that you think that your conviction is unfair. I support crossing in a legal way and I do agree that the law needs to change in order to create legal crossing points for public land access but until that happens I also know that human beings, being what they are, will abuse corner crossings and cause problems for land owners. I mentioned that people have traveled down my property in order to cross in to public land, while that doesn't fit the legal definition of corner crossing, it does however prove that people will carry things too far. One person feels that corner crossing is OK, the next feels that crossing within a few feet of the actual corner is OK, the next guy feels that if it's OK to cross a few feet from the corner then it's OK to cross a few yards from the corner...on and on until you have guys driving across private property where ever and when ever they want in order to get to public lands. And the sad reality is that in order for me to win a tresspassing case in court I have to avoid the possibility of the other side saying that I let other people do it so I have to let this guy do it - that means that I have to deny everybody access or set a precedence of allowing people to cross by direct permission (which I have no problem with).