They do ?
In my experience they will tell you, after you've moaned that every ***ing new switch and socket is now painted, that "that's how it's supposed to be done". Seriously, I've been told that - both by decorators and others. I've yet to find anyone who thinks that loosening fittings and painting behind them is the right way to do it.
Once, when there were painters in at a previous employer, I removed a few things (such as the bracket for a fire extinguisher and some picture hooks) from the wall and left them under the edge of his sheets on the floor. When I went back to refit them I found ... they were already re-fitted and painted over !
Yeah, nothing beats a blank wall to work on.
But I find that there tends to be a hollow around the boxes then. So bad in our extension (not that the plastering is anything but "interesting") that it's been really hard making good where I've been adding extra boxes (for TV, network, etc) alongside the power sockets. In fact, I was finding it so time consuming (I had to dig out what seemed like miles of cable to change runs/circuit arrangement for the lights) that I got a plasterer in - and I think he did worse than I did (but at least most of it is behind furniture).
That's what I do, but then I have no problem doing it myself - many homeowners won't be able/confident/safe (perm any combination) to. And with modern LED bulbs, they are generally cool enough to just unplug from the socket to turn them off.
Of course,