Why Prune Young Young Trees?

I was attending a CHS cheer leading competition for my daughter at Sacred Heart University recently and noticed these Oak trees  in front of the arena.  First let me say that I was impressed with the level of tree/shrub care and the new plantings on the campus.  I noticed these trees side by side and they are a good example of why younger newly panted trees should be pruned.  The tree on the left has two competing co-dominant leaders.  There is a higher probability of the tree splitting apart in higher winds.  One of these leaders should have been removed when the tree was smaller.  The tree on the right has a single straight leader which is much stronger and desirable. Keep this in mind when pruning your smaller trees.