Watering native plants with rainwater... called Xeriscaping, been around since the dawn of agriculture
Well, that definition of xeriscaping understates the amount of water typically used in practice for landscaping in arid regions. Wikipedia's definition is closer - "Xeriscaping and xerogardening refer to landscaping and gardening in ways that reduce or eliminate the need for supplemental water from irrigation. It is promoted in regions that do not have easily accessible, plentiful, or reliable supplies of fresh water, and is gaining acceptance in other areas as climate patterns shift."
My wife and I practiced xeriscaping after building a home in the upper Mojave. It begins with using only native plants, or plants from areas which have similar rainfall patterns. Irrigation methods typically use a drip method.
Xeriscaping does require some supplemental irrigation. Without that, it would be extremely difficult to get vegetation started and to sustain new plantings. Without supplemental irrigation, few people would attempt it.
Some municipalities offer financial incentives to residences using/changing to xeriscaping practices.
