Many are, but they aren't true color. The sun is approximately (and it's a pretty good approximation) a black-body emitter, and it's emissions peak in the green part of the spectrum. A black body radiating strongly in the green is also radiating strongly in the rest of the visual spectrum, so it ends up looking white (a faintly yellowish white, but if you saw it directly (through a good neutral-density filter, hopefully!) you'd call it white).

Also the claim that the Sun is classified as an orange dwarf is a new one to me. I was taught (and every source that I can find sides with me on this) that the Sun is a G dwarf ("yellow dwarf"), not a K dwarf ("orange dwarf").