This is not entirely true, there are some deep learning projects that aim to colorize black and white images, the first one I could find was https://demos.algorithmi*****m/colorize-photos/ but this is not the one I read an article about a couple of years ago. While some information is lost, things like contrast etc are not. With this information and some guesses as to what color it could have been it's possible for these algorithms to generate decent looking color images.
BITCONNEEEEEEEEEEEECT!