Because from a gaming perspective we spend more time with Derek, but really if we're immersed in the BaDIK timeline, how long have we been with Derek? 6-8 weeks? He is a completely new friend, yes he is a good friend (sorry Felice) and has helped the MC many times... But Zoey is his friend for several years, the first real one and she helped him become a more or less normal person, and not just another school shooter.
And the reason we see so little of it is the script errors in the Interlude with San Diego and those unnecessary statists from the tattoo parlor.
Zoey attitude in Ep.9 depends on your playground - how you're played her in the Interlude, my Zoey kicks the firefighter douche in the balls and just asks MC to be more careful
In the most routes, I also saw chick Zoey.
And ofc: