Good point. You could argue they’re implicitly not races in some cases. 
However, for many group rides Zwift will tell you that they are explicitly not a race in the ride description or related forum post.
You’ll no doubt have seen many rides with an FAQ question that asks “Is this a race?” with the answer “No…”
Here’s an example: Women's Ride and Run Series 2022 FAQ
Is this a race?
No. These women-only events are socially-paced community rides and runs intended to uplift and encourage women around the world. Ride, run, and connect with the women’s community in-game and IRL.
I guess it can be argued either way whether something like this is implicit or explicit:
Q: Will there be races during the Tour?
A: No, but you are welcome to ride as fast as you like. These are group events and event results won’t be displayed at the end.
(From the https://support.zwift.com/tour-of-watopia-faq-HyMHyrO1c)