English Only

So there are movements (mainly by the right) to have English as the official language of the United States. If I go to any country outside of the United States I am expected to know a the language they speak why shouldn't that be the case here? Living in Los Angeles I would say Spanish is spoken as much as English and I feel I shouldn't have to learn Spanish unless I go to Mexico or any country that speaks it. Shouldn't that be the same here?