Roselvr
Ask me how to get your loved one in NamUs
I would imagine the lights were turned off in the back because she was preparing to close up. OR the perp flipped the switch as he grabbed her at the back door, to keep from being seen more easily. I also assume the switch would be right inside the back door, makes sense to me.
My guess is that this was someone she was acquainted with, maybe someone who was stalking her. She could have recognized them by sight but did not know them well.
As for searches, it's possible that LE has done some searches without the public's knowledge, in the most likely areas. They generally don't do planned searches unless they have an idea where to look, through tips or other leads. In this case, obviously she could have been taken anywhere in any direction.
They do sometimes send out teams of officers to look around in certain places and often the public is never aware that these searches are going on because they aren't publicized. Officers can check dumpsters, alleyways, abandoned buildings, all kinds of hiding places while they're out patrolling, and not even appear to be looking for anything specific. So while it may not look like they're searching, they very well may be.
IIRC; one of the locals went looking for the light switch; could not find it. It's assumed it's in the office.