Once someone's mind is set, it is nearly impossible to talk them out of their opinion by "reasoning" with them. So I don't recommend discussing this further with your daughter. She already knows it's a major inconvenience for you to wait in a traffic jam, and she does not care. You have to make her care. The situation demands creative action, not words. But, she's 12, right? She gets embarassed being seen walking in a cross walk, right? What you need to do is make sure that you look REALLY bad tomorrow morning when you take her to school. If you can make yourself look like you were out all night, drinking, and living it up at a biker bar with a bunch of unseemly men who smoke cigarettes, then you will be on the right track. When you drop her off right in front of the school, where all of her little friends can see, be sure to get out of the car and give her a huge kiss and a hug. Be as obnoxious and visible as possible. If you can, escort her to her first class. Believe me, she will beg to be dropped off across the street in the future. She might even decide that walking to school or taking the bus is way cooler.
I can't wait until my son is old enough to pull something like this with me. Oh, the fun I will have!