> ...laws are lax because oligarchies in developing countries typically don't get harmed by dangerous working conditions.
This holds true even for developed nations. If a particular company or industry can skirt workers rights, environmental laws, etc. and bear the impact as merely a negative return, they will.
> The people with the power to enforce safe workplace laws have no external incentive...
Right, and the only force which affects such oligarchies is unionization. However, as gozur88 said above, feeding your family is more important than any potential health impacts. And when you're in a situation where thousands of others will gladly assume your position, regardless of the cost, there is no feasibly to unionized striking.