Yes, this is true for modern agriculture, because it's an industrial process that benefits from economies of scale. Unfortunately that process is unsustainable and will ultimately deplete our fertilizer resources while damaging the environment.
>Someone working a median wage job will be able to buy more food in the time it takes you to maintain your garden.
Permaculture isn't about returning to peasantry. Permaculture is about integrating food production into society while expending minimal effort (less effort than even mowing a lawn).
>You won't be able to get free fertilizer from people that prune trees because everyone will want it
Fertilizer doesn't need to come from pruned trees. In fact, wood chips alone don't really make for good compost.
Properly designed permaculture systems coupled with local programs such as neighborhood composting and an understanding of the local ecosystem can produce a huge amount of food with very little effort or input.
>Many of them work very little and pay nothing in taxes, use medicare, and are still well off because a lot of their labor is untaxable.
OK, and? Maybe the answer is to reform how we structure society and taxes instead of claiming that low-impact sustainable lifestyles are somehow a form of "theft".
You could make the same argument about how people who refuse to buy a new iPhone every year are "stealing" resources because they don't contribute enough to an economy structured around overproduction and waste. It's absurd.