I’m sure most of you are familiar with the 1950s science fiction depiction of the inner solar system: Venus and Mars both have oxygen atmospheres, water and indigenous life; Venus is a swampy or ocean covered world; Mars’ atmosphere is very thin and cold but humans can still live there with warm clothing and maybe an oxygen concentrating mask. We can eat at least some of the local food, and at least some Earth plants will grow there.
Now, suppose that in our real world this had turned out to be the truth. What would we have done about it? Certainly we would have decided that it was worth it to send at least a few manned expeditions to explore and bring back specimens. But what then?
The 1950s stories presumed the existence of cheap, incredibly effective nuclear rockets. Without some miracle technology to make space travel vastly cheaper, there couldn’t be anything there worth shipping back to Earth. Human colonization would cost millions of dollars per person, and have no conceivable purpose to Earth. Probably at most a few hundred people would end up making the trip and thereafter be on their own, sort of like the Vikings who settled Greenland.
In other words fantasy planets, actual budgets and technology. What do you think would happen?