Hell, slavery hasn't abated since the dawn of man and the only thing that has changed about slavery since the 18th or 19th century is that the slaves were worth more then and the profit margin was lower.

In 1830 US currency, a slave was worth about a thousand dollars ($38,000 current value or about the price of a good tractor). Profit of about 5% per year on ownership was considered par.

Now one can buy a healthy young male for farm labour for about $90 US. Think about that before you bite into your unfairly traded chocolate.