I thought in dash monitors had a wire that was supposed to be connected to the handbrake. So the monitor could not be used whilst the vehicle is in motion. The idea is that the manufacturer builds the safety device in, it's then up to the installer/user whether they implement it. I suppose it's like a car manufacturer putting seat belts in, it's up to the passenger whether they wear it or not. I read up on this legislation when researching DAB radio at uni, something to do with scrolling/constantly updating displays.