Is it a sin to pirate something that isn't for sale? After all, the worker wouldn't get paid for their work anyway.

On my country, Brazil, it's absolutely impossible to watch Azumanga Daioh in legal ways, and there's a playlist on YouTube with the full series subbed by fans. Is it a sin to consume it?

"The laborer has to receive the wager for his work" Yes! But the laborer wouldn't get the money because he isn't selling it on Brazil. Plus, piracy for personal use isn't a crime here.