First the standard of living is a lot lower there so $1US has a lot more buying power.
Saying agriculture isn't economically feasible at that level is fucking ridiculous. Farmers manage to stay in business growing vegetables that are worth far less than a dollar a gram. I'm pretty confident that I could pull around 2kg out of my 4x8 raised bed if I could grow in it. We'll be conservative and say that I could only get 1kg. That's $1,000, I damn sure didn't grow $1,000 worth of vegetables in there this year!