I think Rivian is disguising a hidden factor: CarPlay prohibits vehicle manufacturers from collecting metrics and selling anonymized or identified user activity data, and this loss of telematics data / income stream is unacceptable to manufacturers (for example, GM*) who see the smart TV business making billions on that precise data.

The correct route for someone with interview access to Rivian to clarify whether this scenario applies would be to review their legal terms for owners and then point-blank ask in a recorded interview ‘whether Rivian’s vehicles are reporting to Rivian what music their buyers play in Rivian vehicles’. This is a nuanced sentence: whether is yes/no; information is too broad to weasel out of; ‘on what music’ focuses on a private aspect of car ownership and is a callback to the VHS rental rulings; ‘in their vehicles’ is not only restricted to what’s connected to the headunit by usb or Bluetooth or radio, but also covers the headunit-connected microphones in the vehicle as well. If they say yes, the questions become obvious. If they say no, the followup should be to ask if Rivian contractually guarantees that they will not someday issue a software update that begins doing so. Either it does not, or it does. Two questions max to either confirm or refute a suspicion.

GM cited ‘the ability to improve cars’ as why it’s refusing CarPlay, but as the OP article clearly shows, GM could simply continue to improve the cars and the screen surrounding the CarPlay dedicated window, while continuing to improve their own built-in functions using the data from those who do not use it for the benefit of those same users. GM’s justifications last year in this regard are just as obtuse as Rivian’s this year. Given that similarity, I suspect you’re right: Rivian does indeed seem to be trying not to appear desperately in need of cash by reselling user data for subscription revenue profit: ‘buy our three-ton six-figure vehicle so that we can make $1/year off of you to keep our business afloat’ is horrendous optics and would lead to open mockery of their business.

* The GM/FTC 2026 case only prevents GM from selling data associated with vehicle driving. Headunit usage cannot be readily assumed to be ‘driving’ data in the case context of vehicle insurers, and so continued sale of radio usage data to (for imaginary example) Nielsen would be unaffected by the specific, narrow, and temporary 2026 ruling.

They want software subscription income. It's as simple as that.