And think of the color blind. Especially dark red shouldn't be the only way this information is highlighted. 8% of men are the kind of red-green colorblind, where dark red and black is not easily distinguishable.
The example given in TFA is bad. Red should never be the sole indicator of an error. As you pointed out, color blindness is a thing.
The example should have also put an error glyph (like an exclamation point in a triangle, or the local equivalent) next to the problematic number. Or presented it in reverse, or with an unusually thick border. Anything but color alone.
And think of the color blind. Especially dark red shouldn't be the only way this information is highlighted. 8% of men are the kind of red-green colorblind, where dark red and black is not easily distinguishable.
The example given in TFA is bad. Red should never be the sole indicator of an error. As you pointed out, color blindness is a thing.
The example should have also put an error glyph (like an exclamation point in a triangle, or the local equivalent) next to the problematic number. Or presented it in reverse, or with an unusually thick border. Anything but color alone.