I don’t recall ever saying it wasn’t work, so I’m not sure why you’ve taken the discussion in that direction.

It is work, it’s just not the cynical exploitation that’s being implied. The intent is that both employer and candidate mutually benefit from it. Evaluating the output of these assignments is also work given for your mutual benefit, and it’s typically seen by multiple people, which makes it a non-trivial amount. Both sides do speculative work for the evaluation stage, in that sense.