What does that have to do with red correction markings? . . .
That's an ad hoc observation and might or might not represent reality.
Children learn what we teach them, and if chilcren associate red with failure or less than adequate performance and the lack of a smiley face when they do something right as a slight, it is because that is what they were taught -- they were not born thinking that way. So if children are becoming more sensitive to such things it is because and only because that is what they are being taught to do.
It has less to do with red ink corrections than my comment about blue pencil edits, but to point out that some things change with time. My observation about green and purple causing fewer arguments about seeking partial credit represented my reality, and I'm not assigning it as a solution for universal applications,
so I disagree that it's an ad hoc observation.
I think this is one of those things people get worked up about because they can, not because it matters. If it's wrong, it's wrong, no matter the color of ink.
I'm hopeful 1080Wayne can fix his post above to correct the comment incorrectly attributed to me.