I picked up some Shinto pears at Costco and there were two sizes. One was a larger amount of smaller Asian pears and one was a less amount of very large Asian pears but they both said they were Shinto.
So what does that mean? Some of the Asian pears came off of trees that were not thinned and some got bigger because the fruits were thinned? Same brand too.
They are sorted like Shibumi said. A tree will produce fruit of all sizes no matter what one does. When you have giant orchards, there will be plenty to sort into uniform packs.