At least in the clinic a family member of mine owned, regulation was far from the biggest challenge. It was billing, especially interacting with private health insurance companies. Dealing with their labyrinthine systems costs a lot of money and time.
The private insurance companies are a big factor driving the consolidation, too. As the care networks consolidate their negotiating power, it gives them more and more of a competitive advantage over their smaller competitors, who have relatively less ability to negotiate good rates. That, in turn, leads to them having to drop off of the insurers' networks, which then results in patients being directed elsewhere.
I certainly don't want to say that government influence has no influence, but the brand of capitalism that sees government as the source of all evil is more about politics than economics. Economically speaking, cartels and informal cartel-like systems can be just as harmful. You don't get a healthy, well-functioning market by indiscriminately yanking any one lever; you get it by carefully tending the garden, and balancing a lot of competing considerations.