Oh Daisy, didn't you know ?
UFO's were a marketing strategy embarked upon in the early days of mobile phones. The mobile companies got together and decided that people needed a really strong motivation to buy the phones. So they came up with the idea of UFO's - knowing that everyone would want to catch photos of them but that not everyone always carried around a normal camera with them. So buying a mobile phone would ensure they always had a camera available.
Now that everyone has a mobile phone - the companies have realized that everyone is way too busy texting and chatting on them to bother taking photos - other than 'selfies' - so the UFO idea has been scrapped.