You're probably thinking about jevons paradox. But you slightly mis-stated. It is the phenomenon that increasing the efficiency of resource consumption can end up increasing total consumption.
replyAs you stated it, it would merely be a property of (nearly) all demand curves. Jevons paradox only happens sometimes. It isn't a law.
An example of where it stopped happening is with gasoline in developed countries. Cars having better fuel efficiency doesn’t make me drive further to the grocery store or work.
replyGenerally when someone replaces their vehicle the new one is more fuel efficient than the old one even if I bought the same car.
Jevons paradox: https://en.wikipedia.org/wiki/Jevons_paradox
replyJevons paradox.
replyjevons paradox
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