Sorry but they do.
They’re not my legal guardian, and they’re certainly not the legal guardian of my children
All it takes is the stroke of a pen by a medical practitioner. You are effectively non compos mentis and your child effectively a ward of the state. I'm not talking abstract, just real world. Try it. It will unseal your eyes.
A nurse can’t someone mentally incompetant, on the fly, for someone who is not even a patient. Show me where the law allows that.