Because of spiralling national debt, that's why.It's a lot easier to hide from the eunuch brigade than it is to hide from the only source of safe water and/or food for a 50 miles.
Besides, who's saying we can't do both, and more? A chemical approach, coupled with a manual approach, coupled with necessary gov't services being denied to those still fertile, etc.
We could easily pay for the entire sterilization program several times over simply by eliminating medicare, medicaid and social security. Whatever's left over we can put into the military budget to figure out a way to weaponize the sterilizing agent and bombard every corner of the globe with it.Well I think some cuts in education could be made.
Carrying them to the top of mountains is a waste of energy when we could simply be butchering them and feeding them to the young.Once we institute the program where the elderly and infirm are carried to the top of the mountains to die, we won't need those things anyway.