My friends helicopter mom makes me want to scream, advice please.

One of my best friend's is 18yo (19 in October), she will be graduating her senior year of high school in 3 weeks, and she lives with me, my bf, and our roommate part time, and lives with her dad the rest of the time.

Her mom is the definition of a helicopter parent. She keeps a tracker on her, she has an early curfew for her, she will lose her shit if my friend doesn't respond to her in more then 30 mins. She's not alowed to dye her hair with out asking, she's not allowed get anything pierced (even her ears) she's not allowed to get any tattoos till she is 23. I cant even list every example of how over involved and over protective she is because there is to many examples. And new rules are made all of the time. My friend follows all of the rules.

Today (Sunday), well I was at the gym, her mom called me, freaking out because she hadn't heard from he and had first contacted her 4 hours before calling me. My friend had slept in at my house. I told her that her daughter was safe and that she was just asleep but her mom was still very upset.

The issue is, my friend is very under her moms thumb, and knows a lot of her behavior is not normal, but still tries to justify a lot of it. I know I can't berated my friend with how unhealthy I think her mom and her relationship is, because it won't help but I'm having a lot of issues dealing with how upsetting it is. My friend is just trapped.