One possible answer could be that Democracy worked in Athens because it was a smaller city-state with a more homogeneous population, making it easier for the citizens to come together and participate in decision-making. On the other hand, the United States is a much larger and diverse country with a significantly larger population. This size and diversity can make it more challenging to have direct democracy where every citizen has a say in decision-making. Hence, representative democracy, where citizens elect representatives to make decisions on their behalf, is more commonly practiced in the United States.
