Dad, what I think he was saying when he answered my question was:

You can't collect for practice $8 then collect again $7 for racing. Practice is during the week. Racing is Sunday.

He wants the racers to be able to practice without general practice drivers who aren't staying to race. Your option is to pay $15 to practice on Sunday for three hours, and then decide if you want to race. It's not different than if I hadn't been able to fix our truck Sunday. We would have paid $15 to practice for 90 mins.