Hang on, are you talking about cases like Alfie Evans? Because that case had nothing to do with coat, and was entirely about what was in Alfie's best interests.

Doctors proposed a plan. The parents disagreed with that plan. The doctor's had to go to court to get permission to go ahead.

Contrast this with the US system. Doctors propose a plan and if the parents disagree it is them who have to go to court to stop the doctors.