&gt; And there are crazy pedestrians, crazy drivers, maybe cattle crossing the street, an accident, ice, fog, ice and fog and cattle, unpaved roads, etc.<p>All of which people often don&#x27;t do that well on themselves.<p>&gt;  All those cues and signs were not designed to be read and processed by robots<p>No, but they were designed to be clear and quickly identifiable by humans with vague glances. We&#x27;re not asking for them to identify a subtly sarcastic remark, signs are more of the &quot;BIG RED CIRCLE WITH STRAIGHT WHITE LINE&quot; variety.<p>&gt; I would think an airplane&#x27;s environment when in the air seems more predictable and stable, than an environment for car on the streets<p>Possibly, but the risks are significantly higher. If something unexpected happens you can&#x27;t just come to a halt and put your warning lights on 30,000 feet in the air.<p>&gt;  Same thing for underwater vehicles<p>I disagree on this one, the environment is going to be largely unknown and more importantly for exploration you aren&#x27;t just saying &quot;go here&quot;. When I drive somewhere, many of the roads will have been driven over thousands of times the same day.