Back in the "bad old days" (85-86) my boss and I used to travel with 10 boxes of equipment as checked luggage. A twenty (or two) to the skycap was all that was needed.

If not a public official, I don't think it is a bribe. I'd consider it more "an offer of a tip" -- much like I've often done at a hotel to leave my car out front for a short time or similar.

Now if a TSA agent it could be called a bribe. Don't know about contract security, though.