President Donald Trump's meeting with the Detroit 3 CEOs was a historic bit of political theater -- but it was no dramatic turning point.

Ford's Mark Fields, General Motors' Mary Barra and Fiat Chrysler's Sergio Marchionne convened for the first time together at the White House to speak with the new president about what Fields called a "renaissance in American manufacturing."

But a cooling U.S. sales market, high labor costs and excess capacity at current facilities likely will prevent the companies from breaking ground for new U.S. assembly plants, no matter what enticements Trump offers in the way of lower taxes and less regulation.

More than anything else, last week's hourlong breakfast meeting was proof that automakers are politicians, too. They have images to protect, agendas to advance and constituents to impress.