Your math is accurate for what you said. If you stick to the thought of you're paying for "10 minutes".
However, they have changed it up and I feel it balances out better now. I did another event this past Friday. 1st round is practice, broke up into three 8-11 Kart groups. Second round is stacked by overall fastest of your entire group. This is the qualifier, in three 8-11 kart groups. Third is the finals and it's NASCAR style!! The whole group it split into two groups, by their times. Then each group is on the track for a ROLLING start with a pace Kart. First turn is chaos and super fun. BUT, this is a 14 lap session and they track who finishes in the lead. So to me, that balances out better, and there was a lot more contact = more fun.
Understand, the overall number of people you have could change the break down of things. We had 27 people. Also, after us, there are no more private events there. Yes, they are still caught up in the issues of opening. But, they are not doing anymore until March. People can go ahead and be upset, but at least they are here and doing what they can.