I think you underestimate the difference.
Hitting a stable 30 fps ultimately requires a frame-rate that is well above 30 fps most of the time. In a case like this the average frame-rate on PS4 might be higher than Xbox One - but leaving the frame-rate unlocked would still have produced an unstable update. So, when locked to 30 fps, we're not actually able to see the difference.
These developers are focused on delivering a stable experience at a certain frame-rate - not making one console look better than the other.