The unit has been around since 1999, created to handle mostly fare evasion or Proof of Payment "POP" starting with a group of approximately 20 persons-all transfers from other places in MUNI and most, ADA transfers. All POP occur on the trains only.

This initial group has been interesting, with attitudes like most drivers that people complain about. More interesting that there was no one holding the personnel accountable for their actions. POP inspectors are represented by Local 250-A, the same union that represents the Operators (drivers and cable car conductors / gripmen).

The unit was initially overseen by Michael Hursh, who left in 2005 to another transit agency. Since August 2006, the person overseeing security is SFPD Deputy Chief Antonio Parra