Answer:
Because people in developing countries are less educated and don't understand the implications of being used for drug trials
Explanation:
Drug trials are carried out to test new drugs that companies want to introduce to the market.
The drugs are usually first tested on animals and in the final testing phase human trials are used to gauge how the drug will affect people.
In 1980 the FDA gave approval for testing in other countries. A lot of companies now started using developing countries for their drug trials.
This practice violates the principles of justice because the people in developing countries are mostly illiterates that don't the potential risks drug trials have.
The subjects of the trials are usually given some cash to participate in the trials. They consider it easy money.