A basic economic model is created to analyze a country's overall production. The model includes only two groups: 'households' that supply labor and 'firms' that produce goods. It assumes all firms are identical, all workers are identical, and that the country is a closed system with no international trade. Critique the usefulness of this model for predicting the real-world effects of a 10% tariff on imported steel. In your critique, identify two key elements omitted from the model and explain specifically how their absence limits the model's predictive accuracy for this particular scenario.