Summary: Apparently so! (When I deleted Pandora off the phone that commutes in the car in the morning, I no longer got “another person is listening to your Pandora” on the Sonos.)
I had noticed that the Sonos would stop in the morning every so often. Weird. On occasion it would say the Pandora notification (I typically use Pandora) “another person is listening to your Pandora account” or whatever it is exactly. Tech is so complex these days, I didn’t think much about it. Important note, I’m more of a Pandora person, my SO is more of a Spotify person (and she commutes in the car with CarPlay in the morning.)
Eventually I realized this would happen a few minutes after she went out and left in the car, and once it happened a few minutes after she texted me that she was leaving the office and headed to the car! I asked if she was using Pandora, she said she did not have Pandora on her phone and she doesn’t use it – turns out she did actually have it on her phone, I am pretty sure I put it there, but she doesn’t use it at home or in the car.
So this morning I deleted Pandora off her phone (after asking, one should not mess with other people’s phones!), fired up the Sonos using Pandora before she left, and the problem did not happen! Granted that’s only a sample size of 1, but it really makes me suspect that for some reason, CarPlay is checking apps and starting them, even if the people in the car haven’t fired up those apps, and that’s why I was having that issue with Pandora (having it occur on the Sonos added an extra layer of complexity to what might be happening). I don’t see how that Pandora error could happen without the app starting on some other device, and the timing with her and the car several times appears fairly solid to me.
I assume there is some good reason for that behavior by CarPlay (if indeed that is what is happening), but it was definitely confusing.
If anybody knows, is my hunch correct? If so, why does CarPlay do this? (I mean I could Google, but I prefer the community of actual people and good discussion here. And sharing a decent Apple-related mystery!)