Anthony,
Some aircraft use different idle settings, others don't. Generally that's an engine function, rather than an aircraft function; airframes tend to use a variety of engines either as a customer choice or just as the airplane evolves...and what's an option on one engine installation may not be the same on another...even though it's the same type airplane. The B747, for example...three different basic engine makes to hang on it, with differnt models engine from different manufacturers.
I flew the C-130. The early models I flew didn't have a ground idle. These were turbopropeller airplanes; the T-56A-9 engine had no ground idle, but the T-56A-14 engine did. It was quieter, cooler, and burned less fuel on the ground. As previously mentioned, in flight, a higher idle speed means the engine spools up faster, and is less likely to flame-out...as well as producing more bleed air for pressurization, air conditioning, anti-ice, etc.
At low engine speeds, small openings have to be used in the engine, sometimes called acceleration bleeds, which dump air out of the compressor to keep it from stalling. As air enters the engine, it's compacted or compressed, and pushed through a series of stages which continue to do so, before it's slowed, pressure increased, and then fuel added to burn. In those compression stages, an orderly flow of air is necessary; increase the pressure too much without enough airflow, or allow the blades to turn slowly enough, and the airflow in there stalls; it can reverse direction in the engine, the flame in the engine can go out, and somewhere in there, engine damage can also occur. The acceleration bleeds are small valves which open to let some of that pressure out when the engine is operating at low speeds.
Wasting this compressed air in flight is pointless...especially when the bleed air is used for so many functions in the airframe. Preventing the engine from going so slowly as to open these bleeds is an important operational consideration, then, and is designed into the operating design of the engine. Some engines revert to ground idle on their own after touchdown, others must be put there manually.