What does it mean to be expelled from a driving school and become a self-taught person?

I didn’t go to a driving school and learned to drive on my own.

This sentence is a slogan on a car sticker. By saying that I have never been to a driving school, I ask the cars behind me not to get too close to each other, so as not to be intimidated. Used to remind cars behind to keep distance and pay attention to safety.

There are also some reminders to keep distance between cars, such as: 1. Keep distance, don’t force me to deform. 2. God is in the car. 3. Add milk, not oil. 4. I'll leave first, and you'll wait later. 5. No matter how good the brakes are, they can't stop my inspiration.