The oil needs to be changed "more often". Because, in short and local trips, there are times you have to stop more than you would as compared to a long trip, mostly due to traffic. These doesn't allow time for the engine to warm up properly, thus changing the viscosity of the oil. This will lead to improper greasing of the car parts and eventually damaging of the car. Same goes for driving on a dirt road, the particles in the air can get into the oil and thicken the oil, thus no proper oiling of the car parts.
