[estimator7292]

Guessing passwords is an attempt to access privileged information you have no right to access, and could not otherwise access without bypassing security measures.

Guessing a URL is an attempt to access (potentially) privileged information which was not secured or authenticated to begin with.

A password is a lock you have to break. An unlisted URL is a sticky note that says "private" on the front of a 40" screen. It's literally impossible for that information to stay private. Someone will see it eventually.