They're over the limit?
Sorry, whatever the ultimate cause of the accident, they were unfit to drive, thus pontificating over what they "would have" done in another is absolutely pointless. This driver got into a car and drove off when there was even a RISK of being near or over the limit and never questioned it.
They are, therefore, a BAD DRIVER. The cause of their death - whether that's a guy on the wrong side of the road, unintended acceleration, a fire, etc. is incidental to their decision to drive. That's why we make brakes and steering wheels and train people to pass a test to ensure they're fit to drive, so you can avoid obstacles, stop the car, press the right pedal and not lose control if you're being a driver of even satisfactory driving skill.
Yeah, it's sad. Yeah that kind of acceleration is unnecessary. Yeah, maybe there was a guy on your side of the road - it happens, there are idiots everywhere and people use the other side for overtaking, manoeuvres, etc. all the time. But the driver drove a car without knowing its capabilities, or feeling discomfort at it themselves enough to NOT drive it, or without taking "due care" (a phrase that will come up a lot) to ensure they didn't accelerate unintentionally no matter the situation. And they chose to do so while their judgement was impaired beyond legal limits.
Contributing factors are the least of your problems, compared to telling your OTHER sons and daughters, and their friends and family to NEVER DRIVE DRUNK if they don't want to kill themselves and others.
That you have to state that to an adult is really a sad state of affairs.
If it had been on a Harley (there are electric Harley's now too!), and they'd done the same, would you be calling for motorbikes to be outlawed where you weren't saying that before? The device is not the problem - someone pressing the throttle when they mean the brake is never going to end well, even for a fraction of a second. The problem is that you have allowed yourself to bring up your children to think that drink-driving is fine and acceptable, even if you know it's illegal, and then blame others when your KILLER of a child takes someone else out too by driving drunk.
Fuck, I don't even let work colleagues do that. I have literally removed people's keys and they've started fights with me over doing so. If your own child did it, fix that problem before you look at ANYTHING else.