I get the impression that the bits very obviously behind cabinets is considered OK not to finish to the same quality. It's the first bit where I've had a hint that the builder may be human after all.
its also about costs, at least in my view. Wouldn't you be pissed if painting behind the cabinets was the reason you had to fork out extra on a new tin on paint?
He's certainly mist a bit around the pipes.