According to dependency theory, poor countries have become dependent on rich nations because

The dependency theory is a model of economic and social development that global inequality in terms of historical exploitation of poor nations by rich ones.
According to dependency theory, poor countries have become dependent on rich nations because poor countries sell raw materials for low prices to rich nations. This is the Historical perspective on the Dependency Theory.

Currently, as of february 2016, an american traveling in france would be by the exchange rate. the weakness of the euro and the strength of the us dollar means that items in france cost less to an american than they otherwise would. of course, if this trend reverses and the us dollar weakens and the euro strengthens, such as was happening in early 2008, an american traveling in france would have an adverse experience because items would cost relatively more.