That's because your eyes are limited. You can only see wavelengths of 380 to 700 nanometers, give or take, and your physical being is limited to three spatial dimensions, so you can't view anything outside of that tiny, tiny range.

You can't see the electromagnetic wavelengths being emitted by that food screen over there. The infrared being generated by your own bodies. Seeing your internal structure, the same way you see the internal structure of a triangle drawn on paper.