You are behind the times. This is a pretty well-studied and implemented thing. It is expensive, though, which is why you don't see if more often. If a motor stops working, you can still drive the car with the other three motors. That's SUPER simple with modern computing and software.

Now, the part where the motors are Ferrari-made... let's see how that turns out.

When a car turns, one side's wheels have to rotate faster than the other side as it needs to travel further.

Thus, it's advantageous to be able to power wheels independently.

All the super-fast EVs from the Model S Plaid and Lucid Air Sapphire to the Rimac Nevera have used separate L/R motors in the rear for some time now, and some have been separate motors for all four wheels. I think that includes some Rivians, and definitely the Nevera.

Keep in mind that having an electric motor per wheel would be nothing like having a gasoline engine per wheel. Not only can an electric motor change its thrust thousands of times per second for good traction control, it can also apply regenerative braking or even just let the motor spin freely.

I assume the cars are at least monitoring the current to each motor constantly, so it's just a programming decision when the LR motor fails whether to go into limp mode vs still sending 500hp to the right rear wheel to see what happens.