Under US labor laws at least, you only have to pay someone if they are doing work that benefits the company materially somehow. They would be forbidden from grabbing bugs out of their queue and saying, here go fix this and maybe we'll hire you. Same with unpaid internships which are _supposed_ to be training and shadowing opportunities only, no actual work being done.

That said, I did just peek and my notes and I read that candidates are paid two week's salary for the coding assignment.

How is it legally different to sitting a one hour interview? You're not getting paid for that either, that doesn't make it a minimum wage violation because its not doing work.

I think their code test / interview process sounds terrible, but the two days of code test is part of the interview, it's not producing code for the company to use.

(I do think that any company that wants applicants to spend that much time should pay for that time, but only for ethical, not legal, reasons.)