Well, it's probably all about details. If I see rocks I can e.g. drive around them, judge if they're really too big for my car, drive on the sidewalk, etc.. =>

Well, it's probably all about details. If I see rocks I can e.g. drive around them, judge if they're really too big for my car, drive on the sidewalk, etc.. => all these options are really complicated to program. Current cars don't stop, at least not in Europe - they might break/go slower but it's going to be mixed with steering to avoid whoever is there causing all that fuzz. And if I think that whoever is in front of me is a threat that I might just run over him/her (or "it" for "animal" - a different kind of complexity - e.g. do you stop for 1 frog? 10 frogs? 100 frogs?) , at least partially.