The stance of most automanufacturers is that they will not retrofit something because if people need some feature they should have just bought the car with that feature.
Also, a lot of features require extra hardware and in today's cars where everything is software, you would also need to pay a "license fee" for that feature....often it needs activating in multiple...Also existing electronic boxes.
Not to mention that a missing feature that requires new hardware, will need connection to the wiring harness and nowadays they dont put in a full wiring harness with a lot of unused connectors.
So basically most retrofits will require them to splice in wires into the existing wiring harness, install hardware boxes and do coding.
This will be more expensive than ticking the box at buy time.