Here's an idea: what if... all drivers may not be exactly the same? What if some respond the same to all cyclists regardless of attire, and others may respond differently to those in full kit? It's almost as though there are multiple perspectives that may be simultaneously accurate for different drivers based on country / state / economic background / time of day / what someone ate for dinner. Nah, that's probably crazy - continue arguing, we'll come to an answer soon I'm sure.