At the bottom of the article:

"In fact, many forest ecologists say creating space to allow nature to do its thing is usually a better approach to restoring forests than planting. “Allowing nature to choose which species predominate … allows for local adaptation and higher functional diversity,” argues one advocate, Robin Chazdon of the University of Connecticut, in her book Second Growth. For mangroves, Wetlands International now recommends abandoning widespread planting and instead creating areas of slack water along coastlines, where mangroves can naturally reseed and grow."

I would also argue, due to mismanagement and improper planning that another reason these fail is because in some areas trees are being planted in areas completely devoid of healthy functional soil.

A lot of times we see photos of people planting in areas that look like deserts, there is a reason the ground looks like that. How is a tree supposed to grow if native grasses don't even grow there? Working on soil health should go hand and hand when it comes to mass planting.