The assertion that all such labor is a voluntary choice on the part of laborers is... depressingly naive, to say the least. And even in cases where it's true,

The assertion that all such labor is a voluntary choice on the part of laborers is... depressingly naive, to say the least. And even in cases where it's true, ignores the fact that many may have preferred not to have had the choice imposed in the first place. E.g. subsistence farmers forced off their land and into cities, either by mandate or through unchecked externalities (aka the polluting plant next door). And purchasing from these manufacturing operations helps spread that misery. I'm not saying it's an easy calculus, but your characterization is surely reductive.