One commonality between the spaces that exist in the back rooms are ones that emulate doctors offices, malls, corridors, pools, playgrounds, etc. all of these are either public or pseudo public spaces (like big box stores). Also there is a nostalgic quality to them, they all exist in a “built in the past” sort of context.
for me it’s more the claustrophobia. the increasing dread of not being able to get out of a labyrinthine space. I’ve literally had nightmares like this, lost and trapped in some winding fancy hotel hallways…