It may or may not still be feasible for these companies if they were paying minimum wage, but that's irrelevant to the fact that minimum wage is a requirement.

It may or may not still be feasible for these companies if they were paying minimum wage, but that's irrelevant to the fact that minimum wage is a requirement. Doesn't matter if the worker is already earning £100k in their main job, and 5 hours of "gig economy" work, those 5 hours are still legally required to hit the minimum wage.