I agree, taking the ego out of driving will be good.
But how should a machine behave while there is still ego present? Tesla will share the road with humans for the foreseeable future.
For starters, don't be in the passing lane aggravating people I think would be sufficient. Or, to MVP it... just an alarm that beeps at drivers who have auto-pilot on if they are in the left-hand lane and a car is behind them but not in front of them. Tesla has all this sort of sensors already so it should be able to recognize that situation that warrants an internal cabin alarm to remind the human driver to use the turn signal and get over.
Tesla has to be mindful of human behavior here. Build software that makes their cars perceived as good drivers by human motorists. What I saw yesterday... the Tesla was driving like an asshole and slowing down traffic. Seems like an easy problem to fix. Too bad we can't have our Dad's ride around yelling at Tesla for a few hundred miles while it learns how to drive "right." Ha.
The behaviour you saw was entirely the fault of the human behind the wheel. He was more than capable of noticing that he was holding up traffic behind him and driving slower than average. There's no need for Tesla to add alarms or special behaviour for this situation because they don't claim to give you full automation right now. There are still some driving tasks that are the responsibility of the driver.
In addition to that, if/when all cars are autonomous, different cars will have different.. temper. Or go at different modes - e.g. eco vs speed. I'm sure hacks for faster or more eco driving will emerge, wether legal or not. Cars should never expect everyone to drive the same and adapt to surroundings err.. autonomously.
Might other cars arrive a little ahead of you? Sure. Is that a problem that warrants significantly different and more dangerous driving behaviour? No.