I suppose, as with "self driving" technology, you have to balance the "nightmare scenarios" with the positive impact and consider the net result. I don't think it would be defensible to disable a car over missing payments, for the reason you describe, but disabling a car because the driver is clearly inebriated would save far more lives than it costs.

But can't mistakes happen with low-tech repossession too?

Of course, but in this scenario you can clearly see the physical asset is gone.

We have an entire legal framework around how to repossess a car, No one knows what's going to happen once you let Tesla remotely shut off your car since they think you might have missed a payment or something.