As it almost always goes -- this legislation restricting direct vehicle sales from manufacturers is only around today because the car dealership middle-man is a powerful money-generating force, and most auto-makers seem to prefer it stays in place.
Tesla got their "carve out" because they had the money to throw at getting made an exception. Rivian should automatically get the same treatment, but we don't live in a country where laws are applied fairly to all.
In many ways, a dealership network acts as a shield to absolve a manufacturer of direct responsibility for dealing with their own defective products. Take Kia as a great example. They've been producing defective engines across a whole line of vehicles for something like 10 years straight. Most managed to hold up through their "generous 10 year, 100,000 mile" warranty but failed soon after it. The landscape is littered with Kia Souls with major engine failures. But dealers act like a filter, putting up barriers to getting them replaced or repaired, despite the manufacturer being legally forced to issue a recall. They'll tell people, "Sorry.. but the recall is only valid if we get this specific diagnostic code from the code reader. Yours isn't showing that one." Each time, the owner has to go to corporate and fight to try to get their engine replaced -- and corporate will counter that the dealer informed them the issue wasn't one indicative of the specific failure that's being recalled. Eventually? SOME people get their vehicles fixed, but a substantial number of others give up the fight, writing off their maybe 8-10 year old vehicle as trash and they buy something else. This constitutes a huge savings for Kia corporate.
It's tougher for manufacturers doing direct sales. They can still reject people for warranty work, or claim recalls don't apply. But now, there's nobody else to blame. They can't just get the customer mad at "Sellum Quick Auto Sales". Now, the wronged customer's response is to never buy from their brand again.