Some patients just need a ride. They do not require oxygen, resuscitation, medications that paramedics carry, bandaging, splinting, or any type of prehospital care. They only need a ride.
Moreover, EMS has no legal authority from the State to detain anyone against their will. Yes, in a few states EMS has that authority, such as under (Florida’s Baker Act.) If the patient changed their mind about going to the Mental Health Facility and wanted to exit the vehicle on the side of the interstate the right of EMS to do anything except let them out was legally unclear. Patients were not restrained (nor was it appropriate to do so), they were not sedated, and if they were medicated it was with oral medications that they had taken for a long period of time. Again, these were medically-stable patients who needed a ride.
Several times there are difficulties on transport service. As you know the back of an ambulance is a dangerous place, filled with sharp corners, cabinets, objects that can be used as weapons, and minimal opportunity for escape. Medics who attempted to restrain patients who decided to leave the ambulance would get into combat, for which they were not trained. The crew size was insufficient to restrain the patient. Most hospital guidelines call for a minimum of five caregivers to restrain a violent patient. Even a radio call for help might not see five or more responders arrive for 30-60 minutes, if ever.