I'm going to guess it's because when you buy a car, you don't buy it from GM. You buy it from the dealer. That $1,500 option can become whatever inflated price the dealer puts it.
While if it's a subscription from GM, it's $1,500 and that $1,500 directly goes to GM.
Why not just include it in the sticker price of the car? At a minimum for PR / Optics.
You could argue:
> Its like power steering. You don't have the option NOT to have it, and it costs us money; so its part of why the car costs what it does.
That way instead of people feeling like they're being cheated out of an extra $1,500 on a $50,000 vehicle; they just purchase a $51,500 vehicle?
While if it's a subscription from GM, it's $1,500 and that $1,500 directly goes to GM.