I agree with both of your statement about bleed being defined and Amazon not requiring it to be colored. But in practice, that's what is happening because they don't seem to see the bleed. I used the template generated by Amazon and here are their requirements:
Page count: 24 to 150 pages
Inside (gutter) margins: 0.375 in
Outside margins (with bleed): at least 0.375 in
That's exactly what our pages are, according to Scribus - see the attached image.
Yet Amazon keeps rejecting our books saying we need to add .125 all around. If we do that, it won't fit a 6" x 9" book template any longer. I first submitted them without bleed, but they rejected all and insisted on bleed, which is now there.
Any ideas?