> for the same reason the effect works in a mechanical DSLR camera

The sensor on the back of a camera is a flat plane, which is why (with most lenses) you get an image where straight lines appear straight. The sensor on the back of your eye (the retina) is curved.

straight lines are straight in a photograph because of precision manufactured optics shaped specifically to achieve that effect, to reduce "chromatic aberrations" and "barrel distortion".