I mean, it's both things. Humans are just really good at agriculture by now. Most countries, even those that we perceive as poor, produce crops well in surplus of their own nutritional needs and can often scale up to produce multiples more.

It's no exaggeration to say we can support feeding 100x the human population with current agricultural land and techniques (assuming you can modify their diets). Largely due to GMO, fertilizers, and industrial farming.