Just a hypothesis but Telsa is a self-driving car platform that just happens to sell vehicles right now.

The trajectory Tesla is taking is where a user buys subscription to a Tesla vehicle, all cars have the same feature set but what is available to you is based on the subscription you've bought. So if you have the autopilot option bought it will be available to you in whichever car that arrives.

In this case it makes sense to push out homogeneity amongst all of its vehicles out there.