Why does golf allow so many different golf balls when every other sport uses one standard ball?
In some high end amateur play/game, and also I believe in the tour, there is an imposed official rule called "One Ball Condition". Uncommon to a regular play, but there is that.
In example, if you started to play a Titleist ProV1 on hole #1, you must finish with the same type/brand of ball. . . Solo, NXT or even if you played ProV1x won't do.