True story:
One of the first houses I ever wired on my own did not have a single ceiling light in it. All bath fans were mounted in the walls and vented down & out through the basement. HO was 'terrified' of the heat loss from ceiling lights and such. Nothing but floor & table lamps on switched receps.
In any event, I still mounted some 8b boxes on 2x4s, flush with the bottom of the ceiling joists, and made notes of the measurements on where those boxes were. I ran 14/3 from them to switch boxes, and dead-ended them there. There was no attic in this home, as the sloped ceiling joists were also the rafters for the roof. Todl the drywallers to ignore them, and cover them up.
Three years after finishing, I get a call from her. She wants ceiling fans installed. I go out, and she tells me she's had three other electicians look at the job. One quoted her $600, another $800, and the other said it couldn't be done. The first two also said she would need to hire someone to patch & repaint the walls as they were going to have to tear holes in the drywall.
I asked if she had the fans already, which she did and they were in the garage. I told her I could have them up and running that afternoon. She said she wasn't prepared to install them today because she would need to empty the rooms out, cover the hardwood floors, and arrange for a drywaller and a painter to come patch the holes she was sure I was going to make.
I told her there would be no holes, and the fans would still be up and running by lunch time. She was skeptic, but agreed. I got my measurements out, dug out the boxes, installed the fans & swtiches, and swept up. Whole job took two hours.
She was absolutely amazed I only charged her $500, and she had no repair work to do.
Did I 'rape' the customer?