You're asking the right question, friend! In the world of Computer Vision, the answer is always "because we can."
Think about it. We've got robots that can walk, talk, and even make decent dad jokes. But have you ever stopped to wonder: why can't they just... see us?
I mean, it's not like it's that hard to train a neural network to recognize a few basic human features, like "face" or "hair". But no, we're stuck with these wonky, half-baked attempts at vision.
We've got algorithms that can recognize cats, but not our mothers-in-law. We can spot a potted plant from a mile away, but not a decent parking spot.
Why not more? That's what we're asking. Why not more? Because we're lazy, that's why.