Time before last I flew, I ended up buying my film at Calumet (remember them?) mostly because I forgot to pack much, and packed it USPS back just fine. I’ve heard rumors of postal service irradiation, but I send out my color film to processors Priority Mail and never any mishaps.
My most recent trip last month (first time flying in half a decade, oof), I was a little nervous. SeaTac has some new automated conveyor contraption for scanning where the guys manning the scanners are in some booth somewhere else. Took a minute to find someone to ask, but they did do a hand scan. Little nervous carry it and my camera bag back to another room.
Flying back out through IAH was same old, same old. Off peak hours, friendly agents that were more than happy to, and chat about photography.
One told me they rarely see film anymore, but it’s not like staff don’t know policy. They have a puffer detector specifically for things that can’t go through X-rays, be it film or medical devices.