While I understand you wish for jurisdiction to be held down more as I’ve seen your municipal jurisdiction post. I will need to remind you that this is a game that does not hold emergency service staffing around the clock. As well as the limited “investigation” topics that can be done through a video game. For example, if someone is lying how would you be able to tell through a computer screen?
I will also preface this by there are many ways to support investigations that include things like traffic stops.
This is coming from my perspective during my 8-month tenure as a law enforcement officer
FBI Police (sort of) serves as a “Patrol Division” for the FBI. FBI has its own investigative team, formally the Criminal Investigations Service, which is equipped with the proper tools to execute undercover operations.
When we consider redundancy, there are certain traits of the bureau that can be considered redundant. However, FBI Police is also equipped with special tools that state, county, and municipal patrol officers aren’t equipped with. For example, every FBI Police Special Agent (to my knowledge) is certified to “gear up” as a tactical operative (assumingly of the Hostage Rescue Team). They equip MP5s and G36cs, and more.
So yes, the idea of FBI Police doing traffic enforcement may be a little odd, but overall it serves more of a purpose than it may seem.