I've read papers about the Rashba effect, Dresselhaus effect, and Dzyalonshinskii-Moriya Interaction but don't understand fundamentally why breaking spatial symmetry is a pre-requisite to see these effective magnetic fields.
I think that you are thinking in their lack of inversion symmetry, due to have a vector product in their definition.
The breaking of spontaneous symmetry is due to have a change of a order parameter which is no sense in this context. And the breaking of symmetry alone is also without meaning if nothing more is said.
I did in fact mean inversion asymmetry. I know that the Rashba Hamiltonian (for instance) is inversion asymmetric, but I'm trying to better understand the nature of the interactions.
Can the Rashba field be discussed from the point of view of band theory? Is it the band mismatch between the neighboring materials that causes the Rashba field?