United Fruit (Nowadays, Chiquita Banana) is the classic example. But monopolies are not necessarily the case. Companies can be legitimate competitors and still tend to move in concert when operating overseas because they have similar interests and a common opponent, the local government. This is also the case when companies represent different industries involved in a major project. When I was in Puerto Rico, many different American contractors were involved in building and financing a nuclear steam plant there, and they were fully supported by American government agencies determined to help them out. Everybody was "working together to get the job done."

It's not necessarily because they conspire to cheat (although that sometimes happens too), they just want the same things and face the same problems. It's not unexpected that they often work together. If the host government is skillful, it can play one off against the other, but usually the companies compete until one has "the concession". Some local politician gets rich and the concessionaire settles down to a long, profitable reign.

The important thing to keep in mind is that this does not happen because a group of evil men sit around a table and try to swindle the little guy. Everyone is just trying to do their job and represent their boss while staying within the law and common ethical procedures. It's just that the system seems to have a mind of its own, outside human control. And it is always hungry. The native sees the natural resources of his country being carried away, a few of his politicians and businessmen get very rich, and he winds up with an industrial job that barely keeps him and his family alive while his culture and local economy stagnate. And then the prices start to rise...