Likewise, I can be standing still with my toes on the curb, and then lunge into the street. Should a self-driving car assume that every pedestrian standing at a crosswalk could walk into traffic at any moment, and slow down accordingly? Again, that’s not what human drivers do.
There are a number of surface streets near my house with speed limits of 45 mph, and crosswalks every 1/8 mile or so. Requiring cars (autonomous or not) to avoid any possible pedestrian incident at every such intersection would be a disaster for traffic throughout and a huge step backwards.