The thing is that the people who can not do it, mostly live a very sustainable lifestyle anyway. Subsidence agriculture is basically organic and a lot of permaculture is just repackaging that for a Western audience. Diets are also fairly vegan as meat and other animal products tend to be expensive and if they are not they are usually raised at home.

The people who need to change as their lifestyle is unsustainable have the means of actually changing it to a fairly large degree. Maybe not solar or gardening, but going vegan is certainly possible and even for the two first there are usually ways of finding a workable solution.