ND wheat fields are producing with late 20th c. technology - fossil fuel fertilizers and giant harvesters - and NYC can’t stage the Hunger Games or anything close to it.
We don’t know anything about the technology the districts get to use to produce. We know the technology for living in District 12 is early 20th century, but we know nothing about the technology in the mines, or the tech in the production areas of other Districts. Given that everything is rationed and part of that rationing is specifically geared towards punishment it’s entirely feasible the Capital is sending all good tech to production only. We know 13 has some pretty sweet tech, and 1 and 2 seem to have some good stuff, but we have a very narrow tunnel we get to view that world with, so the overall tech level is only something we can guess at.