They batter themselves with the vulgar conventions of the world, as do all the other things of the world.

I don't understand the wisdom (?) behind the Daoist useless tree parable. We all have to live in the conventional way, which provides a measure of certainty and ease in our lives. Isn't going with the flow, as in taking up conventions, as much recommended to flourish. We can't really opt out.

If Dao trees of substantial size weren't rare, they be considered an bountiful material by someone. There is always a use for a tree unless the constraint against using it is absolute (law). The specific nature/property of the Dao tree is in question. Is the wood dense or light, rosewood or balsa. What industry/carpenters desires rosewood or balsa for their customers?

Does the Daoist desire a rose wood cabinet?

Ulaanbaatar (Capital of Mongolia) is famous for having the worst air quality. They all burn coal in their yurts and the conventional activity makes for very severe air pollution. What is Daoist solution for fixing such a problem? No one is moving by coal and exclaiming that it is useless, if that amounts to saying that the comfort of warmth in winter time is useless (temperatures dropping to -20 to -40 °C). The coal sellar/buyer (or whoever) does not walk by and exclaim, 'I'd rather have fresh air and be cold as ice', when the air is already choking.

Does a Doaist burn coal in the wintertime?

If they could all engineer Rocket mass heaters and strive to make living quarters insulated, this would be a step in the right direction, assuming the Jevon's paradox doesn't also arise from such a gain in efficiency. If things are too cheap, folks may have larger families, the number of rocket stoves could increase, and the demand for burning coal rises above the original reduction newly gained efficiencies. But likely the Jevon's paradox applies more to advanced technological economies, where all by conservation of personal wealth (by forced stake in all industry) mandates growth.

The useless tree stands until it is used, like useless coal remains in the Earth until used.

We are more efficient digestors compared to gorillas only if we can mechanically cook/process our food. Our shortening of the digestive system represents a loss of efficiency of digestion if we must eat like gorillas eat but a gain in efficiency if we can cook, cultivate and grow our food. Is this correct?

What mode/process is more efficient than what mode/process given the relevant inputs/outputs. — Nils Loc

This implies that cooking is just externalised partial digestion, as flies vomit digestive juices onto their food and suck up the breakdown products. More generally, 'efficiency' is very often just an externalising of a process. A human with a chainsaw is more efficient than a human with a handsaw, if one ignores all the human effort in building a chainsaw and refining the petrol and so on.

Thus the search for efficiency is motivated by laziness, which is the great engine of progress. Most people will work like donkeys; only the lazy will take the trouble to arrange for donkeys to do the donkey work.