[belorn]

bacteria in a jar grow and populate uniformly. Humans don't and tend to clump up in high population areas. Human population growth also tend to slow down with economical stability which is the opposite to bacterial growth.

As for mars, what we really need is to build technology that can make inhospitable places livable without infusing additional resources. A key point is water extraction, which would make a lot of desert environments much more hospitable with the right technology.