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The aberrations most likely to be produced by an eyepiece's inability to handle the lateral rays of a wide, shallow, light cone of a short f/ratio scope are astigmatism, lateral magnification distortion, and lateral chromatic aberration, not to mention spherical aberration. Coma CAN be produced by a simple lens (say, a one-element eyepiece (not common since the 1600s). Coma, however, is solely an aberration, with today's eyepieces, of the mirror.
I agree that individual variation , such as the genetic abilities to see in the dark, plays a role in the visibility of coma, but the size of the star image at the edge of a 40mm focal plane in an f/5 scope is literally 9X the width of the Airy disc. It's hard to believe that anyone could be unable to see it. I suspect that everyone can SEE it, but not everyone is BOTHERED by what they see. That's a psychological response, not a physical one.
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