Could it be that you might have grasped the text clearer had it said the people instead of the people in the free market?
People act according to their environment and stimula.
I'll ask again.
1. How do the people in a free market system avoid the destruction of the inhabitable planet from which we depend on to survive?
2. How do the people in free market system ensure that no people will starve unnecessarily?
1) They grow their own food, work near their home, drive electric vehicles, have solar panels in their homes, recycle...
But the market produces what people value. If people demand self-destruction we're doomed no matter the system.
2) Why there's no full employment?
Why homeless aren't hired for food wages?
Of course, first of all, there's violence and wars. That's the case of many countries in Africa.
Then there's regulations, for example, minimum wages laws that prevent the less productive people from working.
And finally there's capitalism.
With capitalism you don't have only to produce as much as you're paid, workers are treated accounted like rented machines (capital) and (as I explained earlier) they have to be as productive as money or they won't be financed. The productivity of the monetary capital is the interest.
This way interest prevents full employment.