The Guerrilla Grafters see the trees in their city as a missed opportunity to provide fresh, healthy and free food to the people. That is their philosophy.
This practice is illegal, so they do it clandestinely and secretly. If we think about it, it would be incalculable to know how many resources are allocated to the maintenance of ornamental plants in the cities, when in many of those same cities, there are families who cannot have access to seasonal fruits and vegetables due to their low economic resources.
Once a tree is grafted, they notify the community to take care of it and take charge of harvesting the harvest. In this way they prevent the fruit from falling to the ground, generating dirt and pests.
They are also looking for people all over the world to join their movement, on their website they teach you how trees are grafted and some other useful tricks that you can use in your garden. And they are getting it, on the map you can see how they are spreading throughout the world, especially in the US, their country of birth.