Comment by micromacrofoot

Very true, I would also caution this with test projects with real humans in the hiring process. Comparing one-shots from actual people is unfair too, and often the most valid assessment comes with giving them feedback and seeing how they respond to it.

Aside from that point: if you are reading this and making people do a project as part of the hiring process, you should absolutely be paying them for their time (even a token amount).