Primarily, the employer benefits - which is particularly evident in this case. They can ask the applicant to do the work to prove themselves, with the pretence

Primarily, the employer benefits - which is particularly evident in this case. They can ask the applicant to do the work to prove themselves, with the pretence of an available job, and don't even have to consider the result of that work. This scenario lays bare that the employer has all the power in the situation.