It is good to compete until prices drops super low.... technology drives efficiency and offers better stuff at greater quality tities for lower prices. It's not actually helpful to overpay for things just to ensure a living wage. This living wage is at a lower standard of living. You don't build a building with a thousand men with shovels because someone else will build one nearby using bulldozers. Consumers would rather preserve their own hard earned money than overpay in order to grant someone else a higher than necessary wage.
That's all well and good from the consumers point of view. It doesn't help people who are spending their working hours at a place that cannot support them. It's not about doing things less efficiently, so your 'building with shovels' example is facile. The point is that companies alone cannot be entrusted with the welfare of their employees - this is why minimum wage and works rights / entitlements exist in the first place. The concern is that these companies are using loopholes to skirt the laws, to the detriment of citizens.
I'm sure you'd agree that citizens rights should trump those of consumers who want cheap stuff.
