Actually, according the paper I cited, it’s often better than 95%. Of course there is overlap in facial features, and if such an individual dresses and behaves as the other sex they may well go undetected.
In addition to humans, most other higher primates exhibit some degree of sexual dimorphism.
I have had pet rabbits and there is a difference in the faces of male and female rabbits.
Funny that male and female dogs look the same to me, but female rabbits are cuter than male rabbits. And even within the same sex, there is still diverse variation in their faces. Some rabbits are cute, some are ugly, but all dogs look the same to me. Maybe it’s because rabbits are more genetically diverse than dogs?
It’s worth noting that facial contrast plays a significant role in human sexual dimorphism. Figure 3 below shows the same image but with the contrast enhanced on the right, creating a more feminine appearance: