As far as I know, this is not the case for migrant laborers at least, who often get paid more than federal minimum wage (because otherwise they can't get enough people even if they are undocumented immigrants).
In any case, if those were the main two reasons for the disparity, then we wouldn't see the same for other first world countries which have neither cheap migrant labor nor prison slaves. Yet cost of living is still significantly more expensive in, say, Finland than it is in China.
In any case, if those were the main two reasons for the disparity, then we wouldn't see the same for other first world countries which have neither cheap migrant labor nor prison slaves. Yet cost of living is still significantly more expensive in, say, Finland than it is in China.