Robins can see magnetic fields, but only if their vision is sharp

Question: if this ability is so easy to evolve, why don't we all have it? Any animal that moves around a lot could probably benefit from being able to directly sense the Earth's magnetic field.

I wonder if the slanted light/dark bands has anything to do with why birds seem to tilt their heads as they look around.

It sounds like a natural Augmented Reality HUD. Interesting...