The technology is powered and maintained by using the brains and bodies of burnt out psychics. The part that is kept under wraps is not all of them are completely gone but its hard to scream when your body gets cut down to only the necessary components needed.

If they can't be used right away, they are kept in stasis which ensures their minds degrade further because being conscious isn't necessary to tap their powers.

An ernest attempt to come up with non-human alternatives is being taken but nothing beats the genuine article.

It's also being covered up that this is causing the rise of certain phenomenon that could be interpreted as ghosts.