You can't train people to not get distracted, you can only train people to try to avoid distractions like phones or arguments in the car. But regardless how much you try there will always be distracted drivers on the roads.
Being distracted behind the wheel has a lot of cultural aspects - in US driving is viewed as almost a right, else where it is a hard earned and expensive privilege. People tend to value what they had to work hard for. Of course there will be those who don’t, but increasing the barrier to entry to operating dangerous machinery might be a good thing. Look at licensing approaches around the world and you will see places with higher barriers having a bit more order on the streets.