[acdha]

That's a very simplistic view: it assumes that the product in question is an easily-compared commodity, the business has low barriers to entry, and that there aren't other factors (long-term contracts, regulatory requirements, natural monopolies, etc.) which would make switching hard.

In the case of healthcare, consider the cost of entering a competed space: nobody is better at everything so you won't have a clear advantage for many patients, the startup costs (time, money, permits, staff, etc.) are massive, people like to keep their existing doctor and won't change without cause, and the complexity of the problem defies simple solutions. You can't save on staff costs without losing in-demand professionals, things like billing are both intrinsically complex and disastrous if you get them wrong, and so are all of the safety and other regulatory compliance issues. You might be able to shave bits here and there but it'll take time, have indirect costs, and it's going to be a modest percentage over time.