If the shootout is in a low-light situation, then IR-reflective items light up like xmas lights in NODs.

The Secret Service pins are not for shootouts specifically but for access control of secure areas. I worked an event where the President spoke so I got one of the pins once I cleared into the secure area. I’ve still got it in a mementos box somewhere.

Edit to clarify: a matching pin was not sufficient on its own to gain access to the secure area. But being in the secure area without a matching pin would certainly be sufficient to draw some official attention.

RFID is more for tracking an asset, in this case a human, in a building I suspect. You know someone passed a sensor at a certain point, someone in a command center can go "that person isn't supposed to be there, challenge them now".

IR says "this guy I have in my scope from my perch on this nice rooftop does not appear to be a friendly", as well as via fixed camera or drone.

The IR Signature Control Low Emissivity Tape used by militaries says "oh they're reflecting IR in the correct pattern" by someone using NODs, cameras and scopes that aren't filtering IR, etc so when you see a bunch of people running up on you at night (or even during the day) and for whatever reason they aren't shouting or radioing the equivalent of "it's me, don't shoot!" you don't mow them down with a hail of bullets only to find out you just slaughtered a bunch of friendlies.

It doesn't hurt. There is no budget constraint to preclude it. It can help when overhead surveillance is providing intelligence via radio to agents on the ground or when night-vision gear is in use.

Any epsilon of benefit is probably deemed worthwhile.

RFID is probably used for crowd control / helping agents determine who's allowed access to assets.