My understanding is that Tesla disables remote access on cars when they are brought in to service centers in order to prevent the owner from randomly beeping the horn or opening the roof or other silly stuff. I can understand their position on this, and I don't advocate removing that from them.
However, I also feel that even if actual control can be disabled, it should not disable tracking without a PIN or password that is set by the user. Meaning, when the car is in for service, you can't beep the horn, but you can still see where it's at. This, I think, is a fair compromise to meet the requirements of being able to easily track it when it is stolen without the thieves being able to disable that tracking, but the service centers can still avoid randomly beeping cars.