I doubt we'll ever get data to support this but I suspect most drivers aren't drivers for very long. A few, who are otherwise entirely unemployable, may stick it out. It sounds like a much better deal than it is, I think most people realize that after a relatively short time.
My experience with doing deliveries was the only people who had been doing it for a while were a: broke as fuck and 2, exactly the opposite of the type of person you might want handling your food.
