Yes, I think they could have gone with any color as long as they were going to use that reflective paint, but the red was chosen because it looks retro branded as "Disney". (much like the Magical Express buses). I don't believe that the red was necessarily needed to cover the reflective stuff though, they could do the same in yellow or purple or orange or whatever. But red goes with the Disney color scheme. I don't even believe it was used so the bus stands out during the day as the bus is grey, the windows dark, and the paint red - so not a whole lot of contrast there - but realistically - I think no one is going to miss that bus. So again, I'm pretty sure the red was simply aesthetically pleasing and branded.