... provided you own land that the government allows for agricultural use. And most people can't afford to own enough land to be self-sufficient.
So you're not free to grow your own vegetables either; just like fishing, farming is regulated to manage limited resources. Things get ugly fast when you start raising pigs in your city apartment, or start polluting with pesticide runoff, or start diverting your neighbour's water supply...
You can grow some amount of produce, if you have a garden, but a lot of people don't have their own garden, and if they do it's quite small. To be entirely self-sufficient, you need quite a large area of land just to grow enough food for the entire year.
Most people don't have that, and can't afford that, hence why they take the route of earning money some other way, and using the money to buy food made by others, from supermarkets. They can supplement their diet with home-grown fruit and veg, but few can sustain their family on home-grown produce.
So you're not free to grow your own vegetables either; just like fishing, farming is regulated to manage limited resources. Things get ugly fast when you start raising pigs in your city apartment, or start polluting with pesticide runoff, or start diverting your neighbour's water supply...