Eliminate physical cash and physical mail.
The Centralized Control Model
NYC JAILS WANT TO BAN PHYSICAL MAIL, THEN PRIVATIZE SCANNING OF DIGITAL VERSIONS
Authorities say banning physical mail will stem the flow of drugs, but most contraband behind bars comes from other sources — including jail guards.
https://theintercept.com/2023/01/23/nyc-jail-rikers-mail-surveillance-securus/