In the United States, how do employees let management know their stakeholder concerns?

In Germany, under the model of “stakeholder capitalism”, employee representatives sit on company boards of directors. In the German model of business, it is assumed that both labor (employee representatives) and capital (shareholder representatives) have important stakes in the enterprise and should work in harmony with each other. In the United States, the board of directors usually represents only the owners of the business. What advantages are there to employees as stakeholders in Germany that are not provided to employees in US companies? In the United States, how do employees let management know their stakeholder concerns?