Swifter, yes. Better? I think that depends on the particular circumstance. For example: you look in your rear view mirror and notice an out of control cement truck half a block away heading directly towards you, plowing through vehicles in its path. Would a computer recognize the impending catastrophe and take the initiative, sideswiping a few vehicles in your way in an effort to get out of the situation?
I think it's safe to say that every day driving circumstances are already on par with what a human driver could achieve. It's the extenuating circumstances where a human can make the call of "my life is more important than property damage or even risking others lives" where I have my doubts. Those situations are obviously rare, but still quite important.
That may be the rational response under certain morals, but not everybody is rational always or has the same morals. Who is legally responsible for those Y deaths? Or, even if there was no death but the car broke a traffic law, how is that addressed? If the Y deaths are disproportionately a distinct class of people from X (say, pedestrians, construction workers), are they going to be eligible for some class action lawsuit? Or will it deepen class divides as poor pedestrians become bitter about being hit by self-driving cars carrying rich people? Are the "drivers" going to suffer guilt, wondering if there's something they could have done to prevent an accident? Are issues like this going to cause the law to require a human "standby driver" ready to take over, canceling many of the hoped-for advantages of self-driving cars? If drivers have legal or monetary liability, are they going to want to hand that over to a machine built as cheaply as possible and designed by overworked startup engineers? (perhaps the first generations at least.) Will the cars keep audit records to prove "who" was driving, etc.?
Maybe some of this is getting off-topic; I'm just musing on how complex the practical and societal factors could get.
>Are issues like this going to cause the law to require a human "standby driver" ready to take over, canceling many of the hoped-for advantages of self-driving cars?
The law can say whatever it wants but there's effectively no such thing as a "standby" (for <30+ second timeframes) for a driving system that's operating autonomously. The driver is watching a movie, reading a book, or sleeping. And if the driver isn't allowed to do any of those things--say by the system shutting down if they take their eye off the road for more than 5 seconds--no, then, the system is largely useless.
In which case people won't pay for it except to the degree that it's essentially an assistive driving safety system.
Mhmmm no.
If you have a machine that is manually operated and kills 1/1000 people due to operator errors, and a machine that is fully automatic but kills 1/10000 people due to software errors or "weird edge cases", it's still the second machine that will never be allowed on the market, because even one instance of it killing anyone will cause it to be fully recalled - doesn't matter that statistically it kills less people than a manually operated one. For automatic machines that number is 0, and automatic cars are unlikely to achieve that.
I think it's safe to say that every day driving circumstances are already on par with what a human driver could achieve. It's the extenuating circumstances where a human can make the call of "my life is more important than property damage or even risking others lives" where I have my doubts. Those situations are obviously rare, but still quite important.