I agree as a Pro-V1x yellow ball enthusiast, but I’ll hazard a guess seniors also purchase TourSoft and TruFeel yellow balls, splitting the demand. As well as why there isn’t a custom number option like with the white balls. Or like this last buy 3 get 1 free dozen not offered in yellow.
I do appreciate that there is a yellow option at all. That’s a reasonably recent option. I tried the rest before but never impressed.