There are actually quite a few of the older R7B family of machines still in operation today around the country (sorry, but can't provide locations). Regular maintenance on them, and they would easily go over 2,000,000 washes.
Although the pinwheel brushes seem strange today, keep in mind that the vehicles being washed today are quite different than those back 30 years ago when those machines were new. There were no sport utility vehicles or mini vans. Most were larger more square shaped vehicles. All of the wash medium on these machines was filament (later machines had cloth options). The side brushes were all short (by today's standards) and would wash just to the top of the fenders or lower parts of the side windows. The filament top brush would overhang the tops of the side windows, and the pinwheels would fill that gap. In the late 80's when the mini vans first came out, we moved to the variants with the taller rear arms.
It's always strange when you look back on product origins when coming from today's perspective. Remember when the "bag phone" first came out?