Oh it’s not just the shades. You’ve got the overall thickness. Also the level and kind of reflective stuff in the paint so it’s shiny when car lights hit it. Just think of how complicated it is to match house paint. And then add 2 or 3 more “factors” to the paint.
Meanwhile in AZ we use completely terrible paint that becomes invisible when wet.
There is Pee yellow, curb yellow, and banana.