Gilded age presidents did not assess the government in the same
way populists and progressives did. how does this event,
"coxey's army," illustrate a turning point in american politics?

Coxey's Army was a turning point in American politics.

Explanation:

During the Gilded Age, Congress had passed a few laws during the time period which is known for political corruption. The structure of politics changed because of this. There was corruption and Presidents used to give positions in the government to political supporters through spoils system. This means that after getting elected, Presidents had enough power to repay the political favors to the people who had supported them get victories with slim margins in cities. It was different from how progressive and Populist movement worked.  

Congress had not passed job creation legislation. Thus, there was this protest march by the unemployed workers during the years of economic depression. The march was led by Jacob Coxey in 1894. It was the worst time in the history of U.S. It marked turning point in American politics and created awareness for millions of people for the change that was needed and bring progressive change in the system.