Funny you say that, same exact thing my mom said about this situation, "She's trying to be a friend, not a mother."
That's true too, and I also attribute it to the early mother thing. She missed out on her youth from having kids so early, so she doesn't identify as the mom, she wants her kids to look at her like she is cool, hip, modern, etc.
Of course when you're the kid in that situation, it's often times pretty disturbing when your parental figure doesn't want to be a parent but instead wants to be your friend.