What is the inconvenient truth that medical robot companies and hospitals will never tell you ?

Do you really want to know this ? 

Please go to the  FDA web page and look at the FDA approval documents of  medical robots.

Informally speaking,  FDA approval is given to the specific-application of a medical robot, not the medical robot itself. That means if a hospital buys a medical robot and does whatever-we-want  surgeries, it violates FDA regulations.