why not "lavori come..."
Si, I have the same question: Lavori come una guardia.
Se devo tradurre letteralmente scriverei: Tu lavori come una guardia. Se devo scrivere "tu fai la guardia" tradurrei: "you are a guard"
Why would "fai una guardia" be wrong. It says you work as "a" guard, not "the" guard?
Because there are two sentence constructions (that I know of :)) that are used when we talk about professions:
Grazie-making note of that-very helpful