Why do most scientists say that UFO reports do not prove extraterrestrial visitors have reached Earth?

How to Report a UFO Sighting (and Where the Reports Actually Go)

Where to report a UFO sighting in the U.S., UK, France, and Canada, what to note before you file, how to rule out Starlink, planets, and drones first, what NUFORC and MUFON do with reports, and the research archives worth knowing.