I appreciate the resources and also sharing your reasoning on why they didn't work.

https://www.mindsumo.com/ seems to be targeted towards corporates over potential employees, as you say it might be because the latter didn't work. https://en.eyeka.com/ seems more focussed, although limited to designers.

Evaluation seems to be the biggest problem in creating challenge platforms for non-tech people akin to hakathons for tech. In Tech, all it takes is to launch the challenge, submit the project, evaluate(which is easier, aided by automations).

How can we create a evaluation metric for non-tech challenges, which makes hosting challenges easier?