< There is absolutely no reason a worker in Bangladesh, for instance, should be paid less than a worker in Silicon Valley, for the same work.>
Of course there is a good reason, we in the dominant western world require that poor people exist elsewhere in order that we can be supplied with cheap goods that we don't want to make ourselves. We were forced to abolish local slavery but fortunately, for us, everyone turns a blind eye to overseas slavery. Capitalism requires a certain level of ignorance amongst the proletariat especially amongst those at a distance...
Our comfort comes at the price of someone else's discomfort, it's as simple as that.