The real but contentious answer is to change our street and urban design. You can only do so much to make a giant metal machine safe for children and small animals to be struck by. Reducing the frequency of cars and pedestrians occupying the same space will go further than trying to engineer the equivalent of a pool that is impossible to drown in.
Do you think that a company that operates autonomous vehicles will support legislation that makes it easier and safer to move around on foot without getting hit by a car? Or will they lobby for car-centric urban design, like many many companies before them?