People looking for somewhere to grow vegetables, are able therefore to use the garden of someone who is unable to care for the garden themselves - and the rent? Giving the owner of the garden a good share of the veg and fruit produced. Isnt that excellent? No money, but everyone benefits: the garden is cared for, people who have the time to grow fruit and veg are able to do so, and the owner of the garden gets some free fruit and veg too.
Here is an article about it : http://totnes.transitionnetwork.org/gard