Because nowadays cars are computers on wheels with lots of sensors, so we don’t need to only rely on human ears and brains like we had to in 1950s.
I think modernizing traffic signals will end up making transportation more efficient and safer. (Just imagine knowing the timing of the next 5 traffic lights on your path.)
This would make roads undrivable by human drivers (unless augmented by modern tech). Probably exactly what you had in mind, but I don't want this future (at least not now)