This is a classic example of what the legal scholar Veena Dubal calls "algorithmic wage discrimination" - a form of wage theft that's supposedly legal because it's done with an app:
https://pluralistic.net/2023/04/12/algorithmic-wage-discrimination/#fishers-of-men
Shiftkey workers also have to bid against one another for shifts, with the job going to the worker who accepts the lowest wage.
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