Even just a "hey, we're genuinely interested and you made it to the shortlist" or something to that effect would just make a world of difference. Now I have no idea if I'm on any sort of shortlist or if they're just shotgunning this to everyone. I tried asking a few times, but I always got such vagueries in return that I might as well not have asked, so I stopped bothering.
Would also help if people made the tests at least a little bit interesting. Now it's either "do this boring CRUD thing you've done 1000 times already" or "solve several NP-hard problems that have been subject of Turing awards within an hour".
The last time I spent quite a bit of time on one of these things because it was interesting, and even put the result on GitHub (with no mention that it was for a take-home test, it "just" looks like any other project, also slightly modified to fit my needs). Then again, what's "interesting" for one person is "boring" for another.