However, the proverb presupposes two things. First, that you are allowed to fish in a particular place for free. But this is not true in places such as Illinois (where I live). I am allowed to fish only if I purchase a fishing license. Second, this assumes that there are fish in the water where I wish to fish. But given our ecological policies, there may not be any fish to fish for; or, they may be diseased and inedible.
Generalizing, in order to get food on your own, you must have free access to subsistence land. For the time being, there are indigenous stateless people who do have some limited free access; the rest of us who live in States, have to purchase or rent such subsistence land.