Okay I've re-read back to your first comment and I think I see what you mean, now.

You mean, that you see gardening as something available only to the wealthy, so discussion of gardening helping with health is of no relevance/help to the question of how to improve the situation for the less wealthy, right?

I see your point. When I chimed in with gardening's 'efficiency', I wasn't trying to think of it as a solution for all people. That said, I do think some of the less industrial methods of farming are worth more effort. Maybe more people having gardens, rooftop aquaponics allotments. Small/local farming collectives. These things can help the balance be more in favour of getting the most health and human benefit, rather than the most money for shareholders and owners.