A basic economic model, which treats all labor as a single, uniform category, predicts that a 10% increase in the national minimum wage will have a negligible effect on the country's overall employment rate. However, after such a policy is implemented, data reveals a significant rise in unemployment specifically among teenage workers in the fast-food sector. Based on the discrepancy between the model's prediction and the real-world outcome, identify one specific, simplifying assumption in the model that is likely responsible for its inaccurate prediction and briefly explain your reasoning.