At my local track jr3 is the second to last race of the night and some nights that means 10 or some nights that means 1130. Our track does a good job of running the young guns earlier in the night but hot laps start at 430 and we have 3 clone class, 3 predator class, stock appearing and open, rookie, jr1, jr2, j3, and senior quarter midget and the younger quarter midget class so as you can tell by the time we start features it is already 8 and to be honest those little 6 year olds up there on the grid look like they could go to sleep in there kart.
There is a reason Jr 3 is on the bottom of the list. Look at the run time on clone 400, pred 400, and others. Races are done in 5-7 minutes. Jr. 3 runs pretty much to their 15 minute time limit every single race because those young folks have more speed than brains.
To be brutally honest, kids classes hurt in my opinion. I love seeing kids getting into racing, but do we really need a class for 5-7, 8-10, and 10-12 and 13-15? IMO have 2 classes of kids. 8-10, 11-13, at 14 run em with the adults. If you want Young kids to have a race, have them run 10 laps at intermission, caution laps counting, and be done.
And God forbid the quarter midgets running here in Southern MO. 5-7 cars total, and they still run 3 different classes, which are all the same kids in the same cars. Imo, QM suck.
What is keeping the turnout low? Races that take 8+ hours to complete. If you can't get your full show in in 5 hours, you have too many classes or you split up your heats too much. Local track is 1/8th mile. Heats are never bigger than 8, features no more than 12. I would look at no class having more than 2 heats. If that's two heats of 20, so be it. A race that starts at 5 should be done by 10.
Tracks that tolerate cheating. One of the reasons I quit racing was because the local promoter told me he knew a few guys were cheating but refused to do anything about it. Don't let cheaters make it impossible to win by the book.
Prep, it's too freaking complicated. Run no prep, and then tire sample on money show nights.
Tracks that have crazy fees more than pit pass and entry. Parking fees are stupid. Truck fees are stupid. Any other fees beyind entry and arm band are stupid.
Racers with bad attitudes. Like OP mentioned, none of us make our living off of our racing. Stop being fighting mad over a kart race. I get it, tempers flair, and I'm just as competitive as anyone else, but nobody needs to lose teeth because they bumped you. Nobody needs to go to jail because your driver nudged my driver. People yelling obscenities at each other in the pits is a bad look and sucks the fun out of it for everyone around you.
That's all I can think of right now for what is hurting the sport. With time I could come up with more.