Cat meowing is not exclusively how cats vocalize. Meowing is a special kitten behavior meant to catch the attention of their mother, and not the language that they normally speak while out and about with other cats.
In this BBC clip from Cats Uncovered, veterinarian Dr. John Bradshaw of Bristol University suggests that cats use kitten vocalizations with their humans as a way of communicating and getting attention. It’s a second language for them.
via Laughing Squid.