Well,
FBI always (normally) handles bank robberies. This is because all banks are federally insured by the government not the state government (the state gov can’t afford banking issues). So yes the FBI does have a job. Secondly, IRL there are multiple units that respond. They do have tac units for robberies and then they have other jobs for negotiations. IRL most units respond, and they all have their own job; PD secures area, tac units watch the hostiles, negotiators come if there are suicidal people or hostages, and then you have snipers. No matter what, everyone has a job, but tac units have a very important job.