It's pretty simple: Dark Matter can't be seen or felt. It probably just travels through regular matter without "colliding", muchlike neutrinos.
It only interacts with other matter through gravity.
Now, we can detect gravity, but only for fairly big and stationary objects. If DM is tiny particles travelling fast, we can only detect aggregate effects on galaxy level.
Maybe it is similar in that the shadow DOM predicts the state of the actual DOM. In this interpretation dark matter predicts the shape of our universe. It might just be how one should go about simulating a universe..!
It only interacts with other matter through gravity.
Now, we can detect gravity, but only for fairly big and stationary objects. If DM is tiny particles travelling fast, we can only detect aggregate effects on galaxy level.