It depends on how integrated they are with their IT-systems. If everything works as it should, they don't ask anything financially.

I don't agree that medical doctors have a business, since they don't have the characteristics of a typical business in that they do R&D for example or meaningfully increase production year over year; it's just labor and the work they do is regulated to the point that there is no creativity whatsoever.

SpaceX is a business, in comparison.

I do know that in many countries doctors form businesses called a practice, but I think in the long term it's going to disappear, for the same reason that Uber drivers are often not considered "independent business owners". I'd say the most extreme form of this is a dentist, because of the completely regulated nature of their operations; everything they do is according to the book. If a procedure becomes surgery, they refer to someone else.

A typical hospital also isn't a business in this sense. A company like Pfizer is a business, because if they mess up it can cost them billions.

One other reason for not counting them as a business is that the number of spots available to study to become an MD is limited, making it a natural monopoly. As such there are no standard market forces and thus there is no business for them to be a business.

I fully expect that the law will make anyone in a medical profession not a business owner in the long term in any sane country.

Just because someone might be good at pulling teeth, doesn't mean they are suitable to be a business owner. If society invests in someone becoming good at pulling teeth, that's what they should be doing; them going over the yearly P&L is not what society subsidized their studies for.

Perhaps in some country like the US nothing is subsidized, but even then there is a huge risk for a conflict of interest and that alone should be enough reason to not make it a business. It should not be profitable to have sick patients.