Reply To: Why does the ray fire from the cage’s edge along the average normal?

Like Spikey, I’m not entirely understanding of how this works.
I would suspect by enabling the cage option in the bake properties may alter the normals.

On further reading, the blender manual says,

When not using a cage the rays will conform to the mesh normals. This produces glitches on the edges, but it is a preferable method when baking into planes to avoid the need of adding extra loops around the edges.

 The inward rays are casted from a version of the active object with disabled Edge Split Modifiers.

The normals (rays) as I understand it, on the cage object the angles of the rays are dependent on position.
Something like this:

These are not exact angles but a guide