The trouble is that if you live in the city then you get all sorts of grime in your hair so you still have to wash all that out with warm water. Because I started to go swimming a lot I had to go back to shampoo to get rid of the chlorine.
That's the clincher isn't it: you can live a simpler life without modern contrivances, but not if you want to live a simpler life without a modern environment. I.e. you can live without shampoo, but only if you live in a log cabin in the hills...
If you live in a log cabin in the hills, you will probably get more dirty than if you had
stayed in the city!