The worst deserts on Earth are still the sovereign territory of other governments, and if you do anything to make them not deserts there'll be a lot of people i

The worst deserts on Earth are still the sovereign territory of other governments, and if you do anything to make them not deserts there'll be a lot of people interested in the environmental impact or planning to come and take/ruin it. Mars is appealing partly because it'll be a long time before it's crowded enough for any of that to matter.