Because, in the same manner that you are supposed to check your mirrors, brakes, tires and what's sitting on the ground behind you when you start your car and pull out, one is also SUPPOSED to check the brakes and tires on a bicycle also. IF the first time you try braking is in a busy intersection, your a friggin' idiot and deserve what's coming to you.....
I don't think a child ever DESERVES to be injured.