You're absolutely correct, it's not difficult. Where you're running into trouble is what a court will rule on. Courts work on reason - what is reasonable. Your car is working fine, and has value which you've received. The court will not order Tesla to buy back a car that is working reasonably well. It's why we have Lemon Laws in many states in the US, which can force a company to buy back a car that isn't working reasonably well.
Here's an example:
Car - $100,000
Tires Upgrade (optional) - $2,000
Seats (7-row optional) - $5,000
FSD Package (optional) - $15,000
If the tires weren't delivered, nor the seats, you would know this at delivery and could refuse the delivery, or have a signed document indicating, as you said, there was some parts shortage and you'll get those items at some point in the future. If they never show up, a court would very likely grant you a refund of $7,000 for the tires and seats, plus possible interest on the time.
The same for FSD. If you argue to a court that FSD was not delivered timely, the court would likely grant you a refund of $15,000 for the FSD Package, plus possible interest on the time.
If you could prove to the court that the only reason you purchased a Tesla was for autonomous driving, and that might be difficult to prove, the court would likely grant you a refund on the FSD Package, and possibly the difference between the price of the car ($100,000) and the FMV (fair market value) at the time of the case (let's say KBB shows your car worth $80,000 at the time of court), meaning you'd be granted an additional $20,000. You could then sell your car to be made whole.
Think reasonable.
