When did the american medical association come into being, after which it began attacking "lay" doctors and institutionalized its authority through standardized programs of education and licensing?

The American Medical Association was officially established in 1847 when there began to be a demand for changes in how doctors were educated and how they practiced. Roughly one year after it's start in 1848 the American Medical Association began their attacks on "lay" doctors in order to reform the medical society in the US.

I believe the answer is: It viewed European interference in the Americas as a threat to US national interests.

It helped colonies in North and South America adopt a democratic form of government.

The monroe doctrine view European interference in America as a form of manifestation of an unfriendly disposition toward the United States.

He believed that all the 'help' that the European give is a camouflage for their true intention, which is wakening United States' government from the position of Ally and slowly taking over control and replace our democracy.