Has anyone ever wondered why Einstein didn’t get a Nobel Prize for his theory on relativity?
No. This is well known.
IINM, in the first decades of the Nobel Prizes, the prize for physics was only awarded for applied (as opposed to theoretical) physics. So after the Eddington expedition validated his theory of relativity (i think the General Theory, but i’m not certain), the Nobel folk awarded the prize to him based (officially, at least) on his work on the photovoltaic effect, which he did in 1905.