I don't see any backlash at all for the ~90 people that were killed today in the US in motor vehicles [1]. I doubt there will be a massive backlash, unless the vehicles were operating in a known dangerous setup. These vehicles are filled with loads of sensors so accident reconstruction will be trivial.
We've become used to such accidents, and usually blame them on the driver.
In the event of a driverless car killing someone, the manufacturer will have to shoulder the blame; and Google/Uber/etc are much more attractive targets for lawsuits than regular drivers are.
1. https://en.wikipedia.org/wiki/List_of_motor_vehicle_deaths_i...