Free-at-point-of use process tend to be ones that require integration with a billing service, namely, to send information about the performed procedures to whatever system is paying for them, no matter if it's some state agency, private insurance, or whatever else - that's what I meant by non-medical companies that would need to be on the network.

A private practice where everything is paid by the patient in full by cash or CC could do without any integration with external systems (just run a standard cash register), but as soon as someone else is paying for it, you generally need to link the doctor's office systems to that in some way.