[datphp]

Well, take a rice plantation. You need people to cultivate, maintenance, supplies, management. What would those people make on average in the US? 20k?

20k buys you 40t of rice a year on the current marker. How many people do you need on an exploitation to produce 40t/year? 3? 5? 10?

There's your number. With a year's work (doing the exact same thing), you can buy several people's yearly production. The reason for that are currencies.

Without them things would equalize over time (it's happening in EU right now, though only internally). It's a long and bumpy process, but eventually it removes the ability from a country to drain another for next to nothing.

Edit: deleted post said there was evidence a uniform supply pricing was actually bad for poor countries