Doctors just act like they know everything better while the nurses are the ones that see the patient daily and give more information about the patient.
Well a doctor has a higher position than a nurse and likely has more responsibilities than a nurse. They're probaly just afraid that their nurses will mess up which will lead to the doctor taking the blame. Also I'm sure nurses know what theyre doing but im positive theyre still less inexperienced than someone who has been working in the sector for a longer period of time