Yes, planting can be done by hand by folks who can handle the rugged terrain.  But the planting is done once and is expensive.  If the area has a problem with invasive species it will require multiple  treatments while the trees attain a height that can withstand blackberry and scotch broom attack.  This makes the process of getting forest going by repeated hand treatment so expensive that it is not economically viable to even try.  In areas without invasive species problems, the story may be different.