I think the way pinks works is that you tell them how fast your car is, like 11 seconds, 10, etc and you get paired up with a similar car. If you say you have an 11 second car and show up with a 9 second car you'll automatically loose if you run it flat out and smoke them by 30 car lengths. Sandbagging is one thing, but if you bring a 9 second car, you will be pared up with another 9 second car.
Another thing is that it's gambling, you can loose, but the thought of winning is what keeps people lined up to race on TV.