Some of them do, and you can activate the cameras in a lot of cars at will that have front and side cameras. Some of them will auto-brake when going toward pedestrians.
Nothing beats also having actual visible sight line, and there's frequently no excuse for the terrible sight lines of modern high riding passenger vehicles, but pedestrian safety systems are available, and based on technology so cheap in the context of a $20,000+ vehicle that it probably should be mandated at this point.
A lot of cars do have pedestrian detection these days. Even lower end cars like Toyota Corollas have pedestrian detection as a standard feature. These pedestrian detection features automatically apply the brakes when it detects that you're about to hit someone.