I do it at Christmas time. Give gate agents/check-in desk (at my home airport - EUG), to the TSA agents and to the crews of the flights I am on. See's candy (a US West Coast thing) ina sealed one-pound box. Did it in 2018 on a BA flight (SJC to LHR) in First and was thanked by not only the First FAs but the Captain and other FAs throughout the flight as it was passed around. I get the "tampering" thing and maybe there is a policy about not doing it but I still think it is a nice gesture at the holiday season when tempers are high because of crowds and planes full of novice travelers. :-)