In some countries (Australia for one) it is illegal to do electrical work on your house if you're not a licenced electrician. I don't agree with that, but it is a position some people take clearly.
Totally nuts. I get why they want only one ground from a safety perspective but to bring a potential source of a lightning strike into your electrical panel when it can be safely deflected outside the house is insanity to a degree that I'm not convinced it shouldn't be criminal.
Anyway, I refused, they kept on harassing me and eventually (after a year or so) left me alone. I told the guy I'd do it if he would inform my insurance company of the change he requested in black and white, but that of course he would not do. I suspect he became an electrical inspector by following some course, not because he actually understood the first thing about physics.
Highly annoying.
[1] http://www.theguardian.com/world/video/2012/nov/28/dumb-ways...
(Edit: As in, it's not just illegal to plumb your entire house. It's illegal to replace a tap.)
In any case the idea of finding (or even sympathizing with) reasons to prevent owners from accessing their cars' inner functionality rubs me exactly the wrong way.