Why not turn off the lights

Advanced and intelligent life from distant star systems has the capability and know how to build technology to navigate inter galactic travel. So we are talking seriously advanced technology and intelligence. Their ships would need the capability to navigate significant obstacles to reach earth.

So my question is, when they get here and start flying above us doing all their surveillance why don’t they simply turn off their external lights? Why would they need external lights at all? If they’d simply turn off the lights they would go very much unnoticed at least all these lights in the sky sightings would disappear.

I think any sightings that include lights on the ship are certainly terrestrial as we need lights to fly, mostly cause our tech is not sufficient to navigate around other craft without lights, but real aliens intelligence would be much more advanced. Rendering the need for external lights moot.