In other words, you're excluding candidates based on their willingness to expend a lot of their time rather than some of your own.
The screening call goes both ways, ya know. I use that half hour to judge if I want to work at the company, as much as you want to find out if I might possibly fit in. If it looks good, then sure, I might give you an hour for an assessment project.
But I'd never do this FIRST.
I'd do it if they paid me at the proposed salary for my time, maybe.
@mcfate I once was paid $200 to do a "sample article" that I was assured would never be used. That felt fair.
(Though a friend had a similar offer, and the company didn't pay her.)
I'd tell 'em I'd go to small claims court to recover it, with interest. That's horsecrap.
@estherschindler
Small claims court is low-cost and low-effort. The goon employer is the one who's going to have to spend time and money addressing it unless they simply want to lose and have a marshal show up to start seizing things.