What you describe is not 0 cost. You take some sort of cut for services provided, that’s what a private practice does. In exchange for patient flow computing scheduling compliance and billing they charge 30-40% of the patient bill. In a modern work from home environment a provider could contract with a local urban private practice and offer part the hours for the same arrangement. The only real difference is they would have to interview and provide stable ability, the work can be fully remote otherwise. Also typically the practice takes a higher cut if you work fewer hours.