We appear perplexed... There are "Biannual baring" apple varieties; but not "in harmony" with their neighbors! I've heard of Squirrels eating blossoms before they open; and if there were only a few young trees, a squirrel could easily have gotten to (almost) all of them! Late - "hard frosts" will damage "set" fruit blossoms, but not eliminate the flower itself (at least here in Oregon). Too much nitrogen fertilizer tends to cause excessive vegetative growth - too the detriment of "fruit buds." But with several varieties, fruit Spurs vs. Tip-bearers, that shouldn't account for your near total loss?
I'd lean toward the varmint! Have you seen any Squirrel action in the vicinity? Squirrel-guards around the tree trunks? But far from definitive - I'll leave this open to the wiser among us.
As for this seasons lack of crop - lets let them put their collective energy into healthy growth and more blossoms than you can shake a stick at next Spring 
I've seen a similar situation with a 10 year old gravenstein that planted on top of a abandon sepitc drainfield. I speculate the tree receive so much nitrogen that it felt no need to reproduce, it just wanted to grow. Give the tree a couple more years to blossom, if excessive nitrogen is the problem, I believe this can be somewhat neutralized by inserting phospherous into the soil near the tree's dripline.
Many probable reasons for not blooming
1. Type of rootstock, the more dwarfing the earlier to bloom
2. Cultivar or variety differ in when they will bloom, Northern Spy in one that takes a greater age to bloom than others
3. Young trees need to store enough energy to initiate blooms
4. Soil deficiency - Here we lack boron in the soil due to high rainfall. For these small trees suggest about 1/2 tuna fish can of borax soap scattered around root zone (Excess boron is toxic to plants)
5. In general fruit trees require a minimum of 8 hours of direct sunlight–moring sun is better than afternoon sun
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Idyllwild
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