Well if I remember correctly, the badges have a lot of blue in them (I think it was kinda like a teal, almost like Miku's hair color) so blue ribbons might just blend in from a certain distance..Red really pops against blue, which is the reason behind it..Also, when you see red things, it's usually a helpful thing..Think about it, fire trucks are red, ambulances have red as a popping color, those EMT or whatever vehicles are red, things like that, you see the red on helpful things, so it's an instinct or something..