Yeah, one aspect of permaculture is designing systems that do not fight nature. All plants serve a purpose, even "weeds". Its a very fascinating approach and way of thinking. I guess U.S. lawns are our culture's gardens. 

kepford

i guess it depends on what types of plants are in a garden, but i’d imagine the time commitment to maintain a garden would be roughly the same as a lawn, no?

still necessary to do all the watering and weeding, and while gardens don’t need regular cuts, they do need to be harvested.

culture

Why do we all have lawns?

To me it is much less about the land usage and more about the time and money investment. Gardens are very common in many cultures. But we really focus on the lawn.