Whta's the difference between this and robots.txt?

Whta's the difference between this and robots.txt?

Think about it: Most people respect a "private" sign in the real world when there's no physical obstacle, so we don't have to spend huge money on security.

Taking that analogy further:

If you know you have the permission to enter the property marked "Private", you don't have to wait for the owner to come over and take the sign down before doing so. You can just do it.

If you are crossing into the land for innocent purposes (e.g. it's a shortcut to where you're going and the land is unused, so what's the harm?) you might make the decision to enter despite it being marked private. And often that'll be fine, because likely nobody will know, and nobody was harmed.

Think about it. Even when there's a chain-link-fence around some unused land (one step up from a sign on the border), how often have you seen holes in it for people to walk through? At least around here that's quite common.

Both externally-granted permission and innocent infringement are quite common with software, as "in the real world". I've certainly run into both situations personally with copy-inhibited PDFs.