The problem is, conventional agriculture can't feed NY or SF in the long term. It is a system in the process of destroying itself (which is all that the word "unsustainable" means, after all).
Expensive tomatoes are preferable to desertification of the continent (which is what the deforestation, soil loss, and overgrazing due to agriculture cause). What do you think shutting down North America's water cycle will do to the GDP? Compared to paying more for groceries (a tiny sliver of GDP), it's an economic no-brainer.
Then please reference what you mean by $9 per pound for tomatoes and the connexion to permaculture. Most likely you're mistaking permaculture for something else (e.g. "organic") or drawing unsubstantiated conclusions
Expensive tomatoes are preferable to desertification of the continent (which is what the deforestation, soil loss, and overgrazing due to agriculture cause). What do you think shutting down North America's water cycle will do to the GDP? Compared to paying more for groceries (a tiny sliver of GDP), it's an economic no-brainer.