If someone is spending extended time on land that is otherwise completely unused... I fail to see the problem. In this way, "squatting" is like "jaywalking" --

If someone is spending extended time on land that is otherwise completely unused... I fail to see the problem. In this way, "squatting" is like "jaywalking" -- a perfectly normal thing that we invented a crime for (typically on behalf of wealthier people against poorer ones). You can, of course, ask someone to leave your land if you need to use it. There's a reason that adverse possession takes years to decades.