However, if someone is clearly a "pro" with a tripod, telephoto lens, filters and all the other paraphernalia,
Having a telephoto lens, tripod or filters etc does NOT make you a professional photographer, nor someone intent on stealing secrets about on boad service, uniforms etc. I have had all of those things for my old film SLR, and am definitely not a "pro" - just someone who enjoys taking transport-related photos.
MD