True enough, but headlights driving up the mountain cause light pollution for the astronomers working at the observatory (who necessarily need to work at night).

From https://www.ucolick.org/main/visit/info.html

"Please do not visit the observatory at night without a ticket to one of our evening programs.

Lick Observatory is an active research facility, and at night all of the buildings are locked and astronomers are working at the darkened telescopes. Telescopes require the darkest possible conditions to detect the faint light from celestial objects. The success of our work relies upon minimizing lights around the observatory at night. Thank you."