OK I accept the analogies are not good equivalents.
It is not necessarily true that everyone has already paid for the seat warmer hardware. The car may cost the same as if it didn't have the hardware installed. Certainly the owners were happy enough with the car price to buy it without seat warming option.
The manufacturer may find it cheaper to just install it for everyone and wear the cost in the hope that enough people will pay for the warmer to be enabled.
Of course it is possible that everyone pays for the hardware anyhow but it is not necessarily the case.