Why is "Contabili sunt frumosi" wrong? You don't need the article if you are stating a generality. I feel like the definite article is being used far too much in the examples used in Occupations 1 & 2 because they often seem to make far more sense as generalities as they would referring to specific people.
Actually, in Romanian, you do need the definite article to state a generality. The difference between "all accountants" and "these particular accountants" is made solely based on context.
Personally, I feel like an arbitrary sentence with no context is a general statement and all these were poorly translated to English...