Flags with blue

The colours are taken off the picture rather than from anybody's description of it: what the flag is painted in, and how much of it. Each of those is then filed under the nearest ordinary colour word — red, orange, yellow, green, blue or purple round the colour wheel, and black, grey or white when there is too little colour left to name.

So a flag is on this list because part of it really is blue, at the shade shown beside it. If one of them looks wrong to you, it is that rule you are disagreeing with, and the shade is right there to argue with.