Steer clear of it. If this is their mental model of how work should be done, imagine what it is like inside the company.
I would also wonder, if in the US, what laws they might be breaking for this "hiring" process.
That's how a lot of big open source projects like Chrome and Android and React work...except it's more than 100 developers for more than a 8 hours and there is a lower ratio of jobs on offer at the end...and NPM and Github have a similar model except that they profit by aggregating code people contribute for free.
For the app store, developers write code without being paid and compete with each other. The corporate entity behind the competition doesn't pay the losers and takes a cut from the winners and the winners rarely make $100k/year and have no job security because the corporate entity can change the rules arbitrarily.
Or to put it another way, a tournament of 100 developers competing for five $100k/year jobs provides each developer with an expected value of $5k/year/eight_hours. That's an expected value of $612.50/hour. In terms of the App store that's like writing another FlappyBird.
Like I said, the main difference here is the lack of PR polish and the nakedness of the value proposition.
this would have been true if the selected developers didn't need to work for a year and get paid for it!!! you can calculate it by ($100k - $marketRate )/ year / eight_hour !!!
How likely is it that a developer will develop an app in 8 hours with an expected value of $5k/365 or $13.70?
I occasionally get paid to work on open-source projects that happen to help my company. Because you know, it's my job.