A lot of fruits seem to have their varietal information flattened out by the time they get to market (i.e. a yellow peach is just a peach yet there are many kinds of yellow peaches).

Apples have not, and I think that's great.

Is this because other fruit varietals are generally not significantly different? Is there some special sauce behind apple distribution?

In a saucepan, boil 2 c. brown sugar, 1 can condensed milk, corn syrup, 2 sticks butter. Stir constantly, cooking 25 min to firm-ball stage. Dip apples in caramel.

Sorry, couldn't resist.

Something interesting about Apple distribution that i learned recently is that apples are harvested and then stored in atmospheric controlled rooms which causes ripening to stop. This allows apples to be stored for months after harvest and before distribution, which gives us year-around access to apples