>I can imagine scenarios where overpaid tech workers in the US--rather than striking themselves--instead pay underpaid miners (in Africa, say) to strike, which cascades to hold up manufacturing, which cascades to harm their eventual target.

I don't think you've considered the logistical difficulties of what you're describing. It's not like Panasonic has a list of all of the cobalt miners that were part of their supply chain. They themselves have no idea where their cobalt comes from, as they get it through several layers of middlemen. At the root of this supply chain are people like an man who feeds orphans, but forces them to collect peculiar-looking rocks, which he sells to the local warlord's nephew for $2 per hundred pounds. It's not exactly a place that's ripe for unionization. Even could pay somebody to strike, they really have no incentive to do so, as they'd rather earn even more money by not striking and you have no way to keep any individual person accountable.