Why should it? It's illegal, so therefore being under the influence of an illegal substance is an offence as well.
Even if it were legal, I would expect driving under the influence offences to just the same for pot as they are for booze.
Ramming into somebody while driving stoned and crippling them for life or killing them should land you in jail just as drinking and driving does.
In fact, many trucking co.'s have manditory testing for drugs, even the slightist amount of THC will cost you a job at them, and that's fine with me. many life insurance companies will not insure you if you test positive for THC.
That's what I'm asking you---why should it? Does it make a difference whether the intoxicated driver who smashed into my car is high on oxycontin, cocaine, or marijuana?