What looked strange was that I played a game where I never put any meeples into the 3 buildings after initial placement, yet my end of game stats showed that I had hired 5 citizens.
I think I may have figured it out. I don't think that initial placement counts as hiring however, I think that tradesmen are a subset of citizens; i.e., all meeples (including tradesmen) are citizens.
In that case, paying 2 influence to hire a tradesman for an action card would count as both hiring a citizen and hiring a tradesman.
However, if instead of paying 2 influence you hire a tradesman by taking one from a building, then that would count as hiring a tradesman but not as hiring a citizen.
If that is true, I'm supposing then that moving a tradesman from one action card to another would not count as either hiring a citizen or hiring a tradesmen.