Questions & Answers about kono shigoto wa kurou ga ooi.
This is very common in Japanese.
- この仕事は sets the topic: as for this job ...
- 苦労が多い says something about that topic: there are many hardships / it involves a lot of hardship
So the structure is roughly:
[Topic] は [subject inside the comment] が + description
In other words, この仕事 is the overall thing being talked about, while 苦労 is the thing that is specifically described as being 多い.
A natural breakdown is:
- この仕事は = as for this job
- 苦労が多い = the hardships are many
This kind of double marking is normal in Japanese.
Because 苦労 is the thing being described by 多い.
With が, the sentence simply states that, within the topic of this job, hardship is plentiful.
If you said 苦労は多い, it would sound more contrastive, like:
So が is the more neutral choice here.
Very roughly:
- 苦労が多い = there is a lot of hardship
- 苦労は多い = hardship, at least, is a lot / there’s a lot of hardship (in contrast to something else)
