That is because, for historical reasons, they are generally not legally able to. Tesla has actually done great work pushing back on the requirements many states had to franchise automobile sales. However, almost every existing manufacturer has the entire country divided up into franchises and it is a legal nightmare to unpack it.

I’m a little confused by this statement; but here are my service options for my datsun. I can order parts from my local dealer, an online dealer, (and I’ve never tried it but I assume from Nissan), and finally the Nissan Motorsports department.

If Tesla chooses to have no dealerships, then I have to go to them for support.

If I go to a dealership and get ripped off, I can call the manufacturer and they can assist with the problem. Happened to our TSX when the motor was burning oil and the guy who was at the parts shop was saying it was within spec. I had to get a support representative from Honda involved with the repair.

They provide parts to more than just dealerships. There are plenty of auto parts warehouses you can order OEM parts from.