Umm that's called profiling. It's not legal in the US, but happens all the time. What if someone had a car just like the one that you've described and only raced it at the track? It wouldn't be fair getting pulled over for the small stuff, because other people with minivans who do the same thing don't get pulled over. Second: people 16-24 usually can't afford to go to the track. They often require roll cages, fire suits, etc which young people on a budget simply cannot afford. They'd rather mod their cars than spend it on safety equipment.