Here's an example of what I mean by the finer points of traffic law.
(Disclaimer: This is specific to my state. Your laws may be different.)
Here where I live, the Frontage / Access / Service road is not just another surface street.
As the names imply, the purpose of this road is to service the freeway.
Traffic exiting the freeway onto the service road has the right of way, even in a lane change.
Traffic on the service road is alerted to this fact by both a yield sign and a band of isosceles triangles, letting you know you're entering into an area of cross-traffic:
This seems to be too complicated a concept for self driving vehicles, perhaps because it is an inversion of the normal rule.
To be fair though, a lot of human drivers don't understand this either and when it becomes a problem, (i.e. Enough accidents have occurred) the yield sign will be replaced with a full stop: