Direct sales are impossible and it's not because of dealer finance laws. Direct sales are impossible because of us and how we buy cars.
How do the majority (99%) of people buy cars? We go to a dealership and we either buy something they have on the lot or they transact with another dealer to obtain the vehicle you want. Either way, the car you buy is already built, sitting on a lot, ready for your purchase. There is always the opportunity to order a car and wait, but that is seldom used. Why it is this way is a different discussion for a different day, but it is the way it is.
How we buy cars is important because of all that inventory we choose from. Cars are really expensive. Automakers shoot for a 70-days supply of a given model in inventory. For something like Ford F-series trucks, that's about 163,000 trucks. Assuming an average of $34,200 per truck to build, that's $5.6 billion in unsold inventory sitting on the liability side of the balance sheet.
Franchised dealers to the rescue. As soon as those truck are built, they are shipped off to dealers who then "purchase" the inventory using floor plan financing. This gets the liability off the automakers balance sheet and spreads it over the dealer network.
This is how cash flow works in the automotive manufacturing sector and franchised dealers are a key in making it work. To change this will require significant reshaping of financials and customer buying habits.
This is where you say: But what about Tesla? They have a successful direct sales model!
Tesla sold 367,000 cars in all of 2019, worldwide. GM sells that many in 3 weeks.
Tesla is a small manufacturer. The financials of direct sales work at this small scale. Plus, Tesla customers are willing to buy cars the way most of us aren't: Placing an order, making a down payment, and waiting.
As it is now, you can already see Tesla conforming to fit the realities of the financial model. The Model Y really has only two options of consequence: 1) Long Range or Performance and 2) 5-seat or 7-seat. The rest is either easily added/removed (trailer hitch and wheel style), color (exterior/interior), and software (full self-driving or not). When the Model S was launched, there were multiple battery sizes, single or dual motor, different suspension types, and so on. Those a la cart options have gone by the wayside with each new model launch. This greatly increases Tesla's manufacturing flexibility by reducing vehicle ordering complexity.
Also, don't think manufacturers won't get hinky with direct-sales either. The more expensive and more profitable Model Y Performance has a 2-3 wait for delivery. The less expensive and less profitable Model Y Long Range has a 6-10 week wait: "I don't need all that performance, but it'd be cool, plus it's only a reduction of like 20 miles in range. I guess I'll spend the extra money, especially since it means I get my car by early-October instead of late-Novermber. "
Kinda sounds like: "I really don't need everything in the Lariat, but it'd be cool and the dealer doesn't have any XLT on the lot. It's not that much more expensive. I guess I'll go with what's on the lot."
Of course, we could also add in talk about servicing a car park of millions upon millions of vehicles, parts distribution to both the factory service network and independent aftermarket, and employment of all the people it takes to sell and service 17 millions cars each year across the globe. These are all handled by that independent dealer network.