Pedestrian helmets should be compulsory

If bicycle helmets are compulsory because of the head injuries that cars can cause to cyclists, and not because bikes are themselves dangerous, why are they not compulsory for pedestrians?

Especially child pedestrians are in danger of head injuries from the roo-bars, or bull-bars which are placed on the front of "family cars" at head height for kids. "Head injury is the most common injury type in child pedestrian accidents ".

Let's be consistent. Compulsory helmets for all, always. Why discriminate?

Image: Creativity in public places, Berlin