The car stopping if another car goes before it brings up another issue. If self driving cars start showing up on the road and are recognizable, you'd be able to "bully" the self driving cars since you know it'll always give right away. Imagine being stuck on an on-ramp behind a car that is programmed with infinite patience and extreme risk aversion; you could be sitting there quite a while.
That's not the real issue, that's just the initial domino. The real issue is how self-driving companies will combat that. They'll surely want to record film at all times and have a pipeline to law enforcement to curb suspected bullies. It's often the over-correcting solution that becomes the bigger problem. There are analogues in other human-robot interactions.
Waymo resolved this early on by encoding the human resolution into the action. Stopping as required by law, then moving forward slowly until the next action is more clear.
Imagine if cars were given the same authority to generate citations as redlight cameras and schoolbus cameras. They'd be cheap to free and financed by kickbacks from law enforcement.
I imagine if enough self-driving cars were on the road, that would be less of a problem, because more regular speeds & distances between cars would allow for more opportunities for merging. Perhaps even between-car negotiations of merging or 4 way stop type of behaviour.
I think we're quite a ways away from that though - hopefully not as far away as the flying car thing :)
