That's a fair point regarding balance wrt jobs/devs though the general market would seem to indicate good devs have no problems getting jobs.

But I don't see how it carries over to companies expecting a huge investment from a developer up front (a week's work, unpaid!), without some major positive differentiator from the other companies requiring decent devs.

That isn't going to appeal to any developer with options.

What's the upside, why would they invest that time - just go to the non-presumptive company next door.