[jetrink]

Jevon's Paradox: https://en.wikipedia.org/wiki/Jevons_paradox

"In 1865, the English economist William Stanley Jevons observed that technological improvements that increased the efficiency of coal use led to the increased consumption of coal in a wide range of industries. He argued that, contrary to common intuition, technological progress could not be relied upon to reduce fuel consumption."

[ModernMech]

It's the same reason widening the road doesn't lead to less traffic.