"고용주는 일한 적이 없어요."
Translation:The employer has not worked.
An accurate translation hinges on well-informed interpretation. Going for a verbatim translation that won't automatically give the listeners in the target language the same understanding a native speaker of the base language would get is a bad translation and failure of the job. It can be informative if done with warning so language geeks can see the morphosyntax and pick it apart but it just confuses casual learners and those who just want the info in their target language.
The question is maybe how people understand the respective sentences. When you read the Korean sentence, do you understand it as the employer never having worked in his life? Or that he didn’t do it during some specific time frame in the near past – today or the last week maybe (but maybe he did work before that)? My instinct would lead me to the second interpretation for English “The employer has not worked” but the first one for Korean 고용주는 일한 적이 없어요.
(Of course you can exclude one or the other interpretation with adverbs: 그는 우리 팀에 이동된 후에 일한 적이 없어요. / 그는 평생 일한 적이 없어요. But lacking such adverbs, what would be your interpretation of the sentence?)
My interpretation is that he has never worked in his life. Like LiKenun says below us, the implication is one of "never," but the translation isn't the same thing word for word, just like how in English you say "I have not seen that movie." Of course that also means never, and of course you could change the sentence to use the word never.
그는 우리 팀에 이동된 후에 일한 적이 없어요. -> regarding this, I don't know if one would use 한 적이 없다 in this case. Someone would have to comment, but my understanding of that grammar point is that you would instead say 그는 우리 팀에 이동된 후에 일하지 않았어요.
Googling for 적 being used within a limited time frame find this example: "이별 후 한번도 슬펐던 적 없다" (I have never once been sad after we parted ways). But I agree, unless I wanted to really stress that x has never once happened since some point in the past, I probably wouldn’t use 적 either.
In any case, to come back to our original sentence, I believe that “The employer has never worked” should at the very least be accepted, maybe even be the model solution because just like you said, that is the meaning of the Korean sentence even tough it doesn’t contain the word “never” explicitly. With “not” instead of “never” that meaning is at the very least ambiguous.
Being an employer can be just having money and power to create or inherit a business that that individual or business doesn't add value to, they just take the value from the employees. Or it can be being the owner and the hardest working person there. Or something in between the two. Depends.