Trespassers can recover damages when property owners have willfully or wantonly caused harm or if there is knowledge of frequent trespassing where a particular danger exists. Property owners may also be liable if they fail to warn known trespassers of non-obvious dangers.
For example: A factory owner knows that people frequently take shortcuts across their property where there is concealed dangerous machinery. The owner could be held liable if someone is injured by this machinery and it’s proven they didn’t take reasonable steps to warn or prevent access to the hazard.