Hello,
The tree in the photo does show signs of stress, which looks to  be from improper planting depth. There is no visible widening of the root flare at the ground level. The bark cracking on the trunk is a common symptom of planting or mulching too deep. The following article discusses mulching too deeply.
https://njaes.rutgers.edu/fs099/
Normally,I would recommend carefully removing the sod around the tree out to the dripline (where the branch tips end) and seeing if the root flare (also known as the root collar) is visible. If not, carefully removing some of the dirt over the root system can benefit the tree. An arborist can use a tool called an air spade which can really be helpful in removing soil without damaging the root system. We recommend ISA-certified arborists; find one here:
 https://www.treesaregood.org/findanarborist
After doing this type of work, check to make sure that the area is graded so that there is not a big depression around the tree. While water is important to tree health, poor drainage and puddling around a tree can lead to root rot.
Putting a 2-3 inch layer of mulch around the tree NOT touching the trunk is also beneficial.

With 200 trees this will be quite a project, however, in a majority of cases where trees are planted too deeply, the trees fail before too long. Symptoms like dying branches and general thinning of the crown show up and increase until the tree eventually dies. The "moss" you are referring to is actually lichen, which does not harm the tree, but often shows up on stressed trees due to increased light availability due to thinning canopies.