In the past we had some candidates complain about take-home problems. The primary complaint was that candidates weren't interested in dedicating 4-5 hours of their own time unless they felt that someone from the company was putting in an equal amount of their own time. Some candidates also had suspicions that we were trying to use them for free labor (Not true, we used the same toy problem for every candidate). One candidate even thought they should be able to bill us for their time spent applying (We passed).

Eventually I changed the strategy and offered candidates the choice of the take-home problem or an on-site whiteboard style interview where they solved a subset of the problem in pair-programming fashion with us. Zero people chose the on-site interview. Everyone chose the take-home problem.

No one complained any more after we reframed the take-home problem as the candidate's choice rather than the company's.