What do you propose to do with drivers who are just healing themselves who injure or kill your kids with erratic driving???????
Please post some evidence that pot leads to erratic driving. It is more like uniformly slow and over-cautious from what Ive seen. I think you will find that other substances are involved when driving becomes erratic.
Driving under the influence of ANY mind altering substance is illegal....hence, dangerous.....booze, pot drugs, whatever....penalties should be swift and severe.