I'm guessing he either had not yet gotten into the car or had stepped out for a moment. No, you are not supposed to drive w/o the instructor in a case like this. Of course you are not supposed to drive while drunk in any case. You aren't supposed to run over things to the tune of $6,000 in damage either.

I wonder if he is a professional driving instructor or just a friend doing her a favor. Either way, running over the instructor isn't a very good idea.