This seems to perpetuate the assumption that existence without productivity is equivalent to failure. You are arguing that every square inch of land and human meat has to be constantly productive and efficient. I think the goal for humanity should be enjoyment of life. If we go wholly into other energy production methods (nuclear with battery and aquatic storage, and a sprinkling of solar to power A/C) we can get out of the rat race of mandatory productivity from every living molecule.

Although I don't disagree with the sentiment, there's a difference between using only what resources you need and maximising the 'productiveness' of every moment of your life.

Yes, if you solve the grandparent's problem through fairy dust and pixies, it ceases to be a problem.

GP was pretty clear that they described a "goal for humanity", not a quick fix. Consider all the things humanity has done that were fairy dust and pixies right up until the point when they were done.

GP ignored that the argument was about the environment and straw-manned it into being an obsession with efficiency/productivity instead of life enjoyment.

It's a sentiment you see very often on HN. I wonder where it comes from, and where it might lead us.

How does a shared car not need those items? It is just not under your management and is accounted somewhere else. But they are needed and you are paying for it. The only advantage could be that you're not paying with your own time and then it depends on what is cheaper, your work time or that maintenance time.

A shared car can see more usage, spreading the fixed costs (production, land use for parking etc) over more people.