No, it is because people don't want to grow food. My tomatoes cost me 2 minutes of time. I don't know how much you want to value my time at, but lets say I am pretty awesome and deserve $100/hour. That's $3.33 cents for all the tomatoes I can eat. Where are the industrial farming companies producing tomatoes for 3.3 cents per 100 pounds?
>If everyone had to grow their own food, then everyone would starve to death.
If that were true, we wouldn't exist. People did grow their own food for thousands of years. If everyone had to grow their own food, we'd be fine. All mechanization did was free up people from agricultural labor to do other jobs, humans predate tractors.
>The idea of locally grown food in everyone's backyard is a fairy tale that just sounds nice, but would actually be horrible.
It is a reality for lots of people, and we're pretty happy about it.