Okay kiddo, let me explain what people mean when they criticize NASCAR. Many people feel that NASCAR is not as exciting as it used to be. Some of the biggest complaints have to do with the way the races are set up. People argue that the current system for deciding who wins the races is not really fair.
In NASCAR, the races are split into stages. At the end of each stage, drivers can earn points. Then, at the end of the whole race, whoever finishes first gets the most points, and whoever accumulates the most points over the season wins the championship. Some people don't like this system because they think it's not really fair. They feel like racing should be about who crosses the finish line first, period.
Another issue that people have with NASCAR is the way the cars are built. Some people think the cars all look too similar and that there's not enough variety. They feel like the sport has become too predictable because the cars are all basically the same.
Finally, some people feel like the sport is just too expensive to enjoy. There are a lot of costs associated with running a NASCAR team, and that cost gets passed on to the fans. Tickets to races can be really expensive, and if you want to get up close to the cars and the drivers, you'll have to pay even more.
So, to summarize: Some people criticize NASCAR because they don't like the points system for determining who wins the races, they think the cars all look too similar, and they think the sport is just too expensive to enjoy.