There is literally no reason for fairphone to not include a headphone jack. Beside lining their own pockets. It is easily user serviceable and replaceable. And I'd even argue the the demo this phone is targeted at i.e. ppl who even give enough of a shit to service their own phone would be excited to have a headphone jack. I mean they used to but fairphone removed it when they introduced their Bluetooth headphones. Something that is easily way less "green" or user serviceable than a nice pair of wired headphones.
Everything about them not having a headphone jack leaves a bad taste in my mouth especially in perspective with this companies "misson"