Who in its right mind uses red backround on autocad?

To each their ownI guess

 

I don't use autocad but might be for noticing details easier? I use bright colors on Freehand for tracing things as they are more easy to notice over dark/b&w scans/pictures.

 

I would hope that their color palette is set up such that it doesn't try to paint something in the same color. That could make for some VERY Strange designs...

Long ago in a galaxy far, far away, there were DEC VT-100's. I would reverse the display to black on green or black on orangey yellow. The usual comments were Ewwwwwwwww...

However, there were studies at the time that indicated doing that was easier on the eyes.

 

In a decade of drafting / design, I never once saw someone do that. I cannot even imagine how hard that would be to look at properly.