Studies by credible educational and private institutions have indeed found that consumption does not translate to a greater percentage of accidents, you can't get away with hijacking the argument and making it about whether cannabis has an effect, of course it does that's why people use it. The only thing that matters is whether or not it causes accidents, it is subject to the same rational thinking that goes into determining if a new prescription drug requires driving restrictions, it is not subject to your personal opinions which are derived from a lifetime of wrongfully using the effects of the substance alcohol and related social stigmas as a blanket association for all things which change the human thought process.
There is a wild cocktail of drugs introduced into your mind when you are incredibly angry, for example, right after a breakup. Does that mean it should be illegal to operate a motor vehicle immediately after any argument?