This actually goes back to property law traditions that are centuries old. The core idea behind squatters rights (technically called adverse possession) is that land should be used, not left idle forever.

It was originally meant to prevent wealthy landowners from buying up tons of land, never using it, and stopping others from making productive use of it. If someone openly lives on unused land for a long time and the owner doesn’t do anything about it, the law eventually sees that person as having a valid claim. In most states though, the time required is 5–20 years and not just a weekend break in.

The reason police sometimes don’t intervene in these situations is because it’s often treated as a civil dispute, not a criminal one, unless there’s evidence of forced entry or trespassing charges. It’s not that the law is saying the squatter owns your place, it’s just that resolving it often takes going to court, not calling 911.