Why do domestic cats purr for their owners yet not for other cats?

I honestly think it is there way of letting us knowthat they are happy cats and that they are enjoying the attention. You are right I have recently noticed that about my 2 cats as well. I just lok at it as there way of expressing there love, and gratitude for all we do for them.

I never really realized that but you're right. I have 5 cats and they all purr with my husband and myself but not with each other. I have read somewhere that cats also usually don't meow with each other but they have learned it's a way to communicate with their human family maybe it's the same principle. Maybe they have learned that if they purr somehow they're showing their contentment with us. I also read that their way of communicating is greeting each other by touching noses and licking on the head is a way of saying I like you because it goes back to when their mothers licked them on their heads when they were kittens.