Cats speak to each other through scent, facial expression, complete body language and touch. Meowing however is a language developed exclusively for humans. The only meowing done amongst cats is done between a mother and her kittens. Kittens use their tiny meows to get attention from their mother, which is why once they’re grown, the meows stop.
Cats meow to people for similar reasons. Your cat depends on you and has learned that you do not respond to scent messages or body language. They use meowing as a way to communicate and scientists believe they have refined this language to specifically converse with humans.