The answer is: An unequal distribution of economic power
Globalization calls for open trade between all countries of the world. So that if a country can manufacture something cheaper, they can export to a richer country where they can easily pay the price.
However, there are flaws with this theory.
Many countries are economically more powerful, have better infrastructure and an advanced industrial base. These countries have a advantage over countries which can be landlocked, have small populations, very low resources and low industrial output.
For such countries, globalization might only lead to higher trade deficits and the destruction of local manufacturing.