Moving the controls away from the supply pipes has maintenance, installation and cosmetic implications. Plumbers get their asses burned in the shower just like

Moving the controls away from the supply pipes has maintenance, installation and cosmetic implications. Plumbers get their asses burned in the shower just like anyone else. The controls are directly on the supply pipes because that's the best place to put them when all factors are considered. Moving to motorized valves has it's own host of problems but more importantly most people aren't going to want to deal with the increased installation and maintenance costs associated with having a motor inside the wall of their shower. The main reason you get burned in the shower when someone flushes a toilet is due to a lack of pressure in the cold water supply pipe when the second valve is opened (toilet tank refills) and the pressure in the hot water pipe staying the same. Moving the controls would allow you to adjust the temperature to reflect this but then you'll just have to do it again when the second valve closes and the pressure returns to the cold water supply. A better approach to solving this problem would probably be to attack the water pressure issue so that a consistent amount of water is always supplied to the shower regardless of other devices on the system using water from either of the supply lines.