Chapter 16&17 Curiosities

About still developing countries, if we are being taught that free trade would help them, why are we not trading with them more frequently? Is is because we could get the same good from somewhere else for cheaper, and if yes, then why are we so concerned for them and how they need to get food if we won't help them? Or, are all "still developing" countries not free enough to be able to trade with us? Are they holding themselves back or are the developed countries holding them back by not trading?