Choice Privileges members, beware the Rodeway Inn in Gallup, New Mexico where every room key was opening every guest room.
I suspect you’d find this far more frequently at a small family-owned property than a corporate-owned full service hotel, but it could happen anywhere by mistake perhaps not for every room but for a given room — the one you have.
And even when the issue isn’t so extreme as every room key being coded as a master key, or every door accepting any key, hotel front desk staff can assign someone to the wrong room or give out a key to someone they shouldn’t.