I assume single stage means there is no clear coat over the actual paint pigment. White paint uses titanium oxide (or dioxide) in its pigment to get the bright white coloring and as the chemical name implies, titanium is a very hard and tough metal compound, which is why white paints tend to be a little harder to correct or polish (pun intended!!)
One way to tell if you have a single stage paint is IF the coloring (pigment) is transferred to the pad material (or what even media you are using) during the compounding or polishing process. If it is, you will need to clean the pad (or media) often to prevent marring from this dead pigment being removed. Faded SS red paints were (are?) my favorite for this to happen to.
Who ever says that white paint does not fade has never worked on the above-mentioned manufacturer`s vehicles being left out in the summer sun not being waxed (or detailed) for many years and then you as a detailer get to work on them, because "they always look clean!", according to the previous owner. Vehicles from the deep south and desert southwest are notorious for this.