This isn't just restricted to US. It has become very common even in a country like India for doctors and hospital owners to invite their doctor buddies for 'second opinions' and looking at non-issues and then billing the patients 'consulting fees'.

There is also a huge industry built along the lines of phony testing.

The term used for that think is called 'basin test', basically samples are flushed down the basin and made up numbers are put in reports. You can put in what you like as the doctors know the patient is healthy.