Some states are working on it. The reason it's illegal in most states is because it's an old law that was created to prevent Ford, Chevy, etc. from using their huge amount of resources to force smaller dealerships out of business. It's like how Wal-Mart uses it's huge amount of money to keep low prices until it forces all of the local competition out of business, then raises them once their is nothing you can do about it. Most people want it to go away now though, since it's obviously bad for new automakers that want to enter the market but don't have the mass appeal to get independent dealerships to risk having a bunch of relatively niche cars in stock that never get sold.