Is it wrong/unethical/extractive/in bad taste for companies to require applicants to produce valuable work "for free" when applying? Are there exceptions?

E.g. write an investment thesis, do competitor research, put together a pitch deck, prototype a new feature, etc.

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i guess i'd think about this on the applicant's basis - enough prior proof of work should in the best cases be enough along w verbal interview

but when it's dicey, i guess being upfront about it & requesting candidate for a new proof of work is totally fine ; the candidate can choose to refuse...