People put themselves in dangerous situations all the time. I don't believe for one second that you've never made a traffic mistake in your life, either as a pedestrian or as a driver. But you've been fortunate to be surrounded by others who'll pick up the slack for your mistake and will yield even if they don't have to if it will prevent an accident. The traffic rules don't matter nearly as much as the outcome of people not being killed. Traffic rules are just a means to an end.

So yes, it's quite possible for autonomous vehicles to cause vastly more deaths than human drivers even while being slaves to the rules. Hell, you could do it too as a human driver if you removed your conscience. Just don't hit the brakes the next time you have the right of way and a jaywalker steps out in front of you. You'll easily kill someone within a week and have it be their "fault".