A heated seat subscription makes sense when they sell the car to you as if it didn't have heated seats and are allowing you to purchase them at a later date, much like how Tesla's rear heated seats can be bought long after the purchase of the vehicle. It allows the manufacturer to decrease MSRP $x amount (for Tesla, $300) while also saving money on the back-end by not having to handle more part choices being involved in the manufacturing processes.
The same generally applies for Carplay but it makes less sense given carplay is easy to integrate, only needs to be done once, and is then-on maintained by Apple/Google (for Android Auto), and the measly subscription cost for Carplay most certainly wasn't considered when determining MSRP. The same probably applies for the heated seats argument (did BMW really take into account the subscription costs when determining MSRP), with Tesla probably being the only manufacturer actually doing this since they already take into account things like FSD being unavailable on SR+ Model 3's and no EAP on SR Model 3's, even though all models have the same sensors and cameras and HW3 (although non-plus SR models are no longer being produced, so I'm not sure if they ever got hw2.5 or hw3 included).