Why we cant photograph aliens ?

Hello friends , i love aliens and i like to learn about them ☺️ But i had question in my mind there are so many evidence about these encounters are in our life so many books documentarys but why not nobody could photograph them ? wouldnt it be more easy for example i was listening last news about they landed in the backyard and police also recevied same message but in the comments everybody was saying its not real why there is no photo if they're exist i hope someone can answer im really curious ☺️