Fruit on the Trees and on the Ground

I'm at loss for why our fruit will not stay on the trees. R thinks it's because the tree just are not big enough yet to sustain the fruit.

All the peaches, nectarines, and apricots have all dropped off the trees. Apples, plums, and pears are hanging on. The plums are falling but we still have fruit on the trees. The Stanley plums are doing the best of all the plum varieties. The pears have always done well especially the Asian pears. We didn't spray the apples so they are looking bad but at least 50% are still on the trees.

These next photos are of 3 different types of plums. We have a 4th type, Satsuma plum, but the Japanese beetles have had a sweet old time and have destroyed all the fruit and some of the leaves.
20th Century Asian Pear.

Another variety of Asian pear.The next two are Comice and Keiffer but I don't know which is which.
We also have some tomatoes. Earlier in the week we had our first BLT of the year that was made with one of our home grown tomatoes. Despite the unfriendly tomato weather, we did pick two maters this last week. Even though we planted Early Girl, our first tomato was a smallest Mortgage Lifter and an average size Amish Paste tomato. While taking photos today I noticed several more that are starting to turn. Early Girl was not among them. I guess I must have bought the late blooming variety of Early Girl.Either Brown Berry or Grape tomato.