The first issue confused me . . . the 2nd is shaking my faith in
geometry.

The first is obvious. A table saw cut is only as straight as the side
against the fence. You think a 2x4 come straight to 0.040"? You have to
joint one side and only then cut the second side.

The second; well I don't know what your tool is, but obviously it either
isn't straight or is getting deformed in use.

Tools don't work by themselves; you have to use them properly.