It really is that car dealerships are very wealthy and have a lot of political clout. There were also early rulings that a manufacturer can't order a car dealership how to operate - the basics of the case were that American manufacturers were lending or outright granting money for people to start dealerships. Those dealerships started trying to sell foreign cars, the manufacturers said "no way", the dealerships fought back, and the dealerships won.
Basically it's become a textbook example of the entrenched parties setting up barriers to entry. They have lots of money, and are often active in their local communities, so people generally like them.
Edit: basically, I'm saying it really is too hard to change because the law is on the dealerships side, and there's a lot of momentum and status quo to overcome.
It's a nice cozy relationship. Many car dealership franchises are basically state-granted hereditary monopolies that print money, so of course they are going to put some of that money back into the community (and local/state politicians pockets) to maintain that. It's good for the politicians because they actually have some leverage over dealers, as opposed to a behemoth like Toyota or Volkswagen.
I don't mean this as a joke, but I thought people generally hated car salesmen?
Here in Japan, the manufacturers do actually set a recommended retail price that is slightly higher that what dealers often sell at. Example using the Subaru Outback mentioned up top, shows three available grades sold starting at 3,410,000yen. Roughly us$30k.
They hate car salesmen, yes. But oddly enough "Family Jones Chevrolet/Ford/Toyota/Nissan/etc." has been sponsoring the local little league team for 20 years, so they don't have to do much to convince the locals to tell their state legislators that "protecting" these "family-owned" dealerships is good.
Basically it's become a textbook example of the entrenched parties setting up barriers to entry. They have lots of money, and are often active in their local communities, so people generally like them.
Edit: basically, I'm saying it really is too hard to change because the law is on the dealerships side, and there's a lot of momentum and status quo to overcome.