Short answers, pulled from the story.
Private tax farmers known as publicani collected poll taxes during the Roman Republican period. These men operated outside direct state control and bid for contracts to gather revenue from provincial populations.
From the time under Emperor Augustus, collections were gradually transferred to magistrates and the senates of provincial cities. This shift moved authority away from private contractors toward elected or appointed officials.
The 212 edict of Emperor Caracalla that formally conferred Roman citizenship on all residents of Roman provinces did not exempt them from the poll tax. New citizens gained political rights but retained financial obligations.
After the destruction of the temple in 70 AD, the Emperor imposed an extra poll tax on Jews throughout the empire requiring two denarii each from every Jewish household. This additional burden intensified existing grievances against imperial rule.
Pope Gregory II led the Italian revolt of the 720s because Constantinople Emperor Leo III the Isaurian attempted to introduce a poll tax in the Italian provinces of the Byzantine Empire in 722. Local populations rejected the new fiscal demands with forceful resistance.
King Aistulf of the Lombards instituted a crushing poll tax of one gold solidus per head on every Roman citizen when he invaded the Exarchate of Ravenna in 751. Seeking relief from this burden, Pope Stephen II appealed to Pepin the Short of the Franks for assistance.