It is a common misunderstanding that a Designated Shooting Area is literally just an area that has been circled on a map and “designated” as safe for shooting. There is much more that goes into the creation of these Designated Areas. These areas typically have been specifically designed to increase the safety of shooters and those in the surrounding areas.
Safety measures could include things like man-made berms and backstops, permanent benches or tables that create a single direction for shooting, overhead coverage that blocks the ability to shoot upward or above a berm, and sometimes even sound mitigation measures. Engineers are and other experts are involved in the process of identifying suitable locations for these Designated Shooting Areas and sometimes major improvements to the land have to be made.
See below for some visual representations of what a designed Designated Shooting Area might look like: