Because it's very unlikely the first expeditions will be completely independent of Earth - they're likely to rely on continued support for survival, much like the ISS needs resupply ships. Closed-loop life support probably won't be solved before we get to Mars.
Will humans or Mars abide by the law on Earth? (Score:0)
I think once any of us reach Mars. We instantly start our own government there. Why would anyone work under the authority of the government on Earth?
Re:Will humans or Mars abide by the law on Earth? (Score:3)