> the biggest danger will be inattentive drivers.

I suspect the bigger danger will be vandalism. I will admit that the robots that wander my local grocery store looking for messes to clean up (or at least to alert humans to) make me irrationally angry. They get in my way and distract my attention, and it makes me want to just kick the *$%# out of them. I suspect I'm not the only one who feels this way, and the more robots get 'out in the environment' without anybody watching out for them, the more people will damage them on purpose.