Because if Captain America tells you to do something, and you are not a villain, you damn well do it and are proud he paid attention to you.

I always thought that was more because of his charisma than anything else -- like, when a big guy who fights monsters with a shield orders you to do something, it just doesn't occur to you to say no. But I might very well be talking through my hat. =)

Dear Marvel, you and your so-called canon confuse me.