Based on the blog post saying they're able to use their fleet (i.e. owners of comma) to train their models, it's probably to send footage back home. Tesla does this too btw.
Yep, and it’s why I never bought a Tesla. Also why I haven’t bought any new cars (they all send data home for various purposes, including to sell to insurance companies or advertisers). I’m not adverse to sharing that data necessarily, but I want control over what and when I share at the very least, and without an always-on net connection.