Why would UFO’s need lights and why do we look for lights in the sky to be UFOs?

Been wondering for years now why we are so obsessed with seeing lights in the sky at night doing “weird” things and attribute them to UFOs because I can’t actually imagine why an advanced race with that kind of tech would need lights on their ships when flying through our skies. I mean.. do they WANT to be seen or are they trying to avoid detection? I can’t imagine what the real purpose of having visible exterior lights on an alien ship would be.