You don't need a lot of land to do that. Just 0.25 acres is enough to feed a single person. You can do it basically in a city.

If you're one person who can afford 1/4 acre in a city. If you're married, you need to afford 1/2 acre. Have a kid? 3/4 acre. That's rapidly out of reach of most people.

Then there's zoning laws...