But nobody's asking you to use any of these systems yet. they're in development, not products for sale. There's no benefit to anybody in questioning whether google knows that snow exists, or if uber understands that traffic stops unexpectedly sometimes. Obviously everybody involved in developing self-driving cars understands the most basic definition of the problem.

If google actually starts selling a self-driving car and doesn't give any information about whether it can deal with a policeman-controlled intersection, then you can be concerned. Until then, implying their self-driving car programs haven't considered the basic problems that any uninformed commenter on the internet can think up is not incredibly helpful.