I think it really depends on a lot of things like what airline you work for or what airline you're jumpseating on. I've even had vary between gate agents. I went to one who said I needed it, she left, the guy who came on after her was friendly and not busy and I asked him to check if it said I needed the passport (because I had never had to show it on that airline) and he said no. That was the weirdest.

Anyway, I always carry it with me because I don't want to get in the position of needing to have it if it's not on me. It would really suck to want to get home and not get on a flight because you don't have a passport.