In the higher areas of Managua, you will find restaurants, continental hotels and rich people. You will usually find the middle class and the upper middle class living closer to the malls. People prefer that because they can easily go shopping, dine at restaurants, watch movies in the cinemas and experience some nightlife.
If you go to the lower areas of Managua, you will find the middle class, lower middle class and some poor neighborhoods. This is where you will see fritangas, which are open restaurants that cook meat on a grill and serve them with some gallo pinto and bananas. Eating at these is very low cost.