This is a super simple setup, the elevator has both a north and a south door. but the ground floor (0) only has a north exit meaning that they never added a ground south floor. but they wanted aesthetics over functionality so instead of having an empty button slot and moving everything up, they changed the number so the south wing starts at 1 and north wing at 0

Considering a lot of gore content is illegal in places such as the US, it’s possible they the tag doesn’t exist anymore on most places to avoid promoting the content.