No. It's because we have to account for every round fired and need to make sure that they are going into the berms. A round fired low and skipping off the dirt is just as bad as a round going over the berm.
Everyone says "but I can control it", ok, you may be able to control it, but the guy next to you just bought his rifle and copies what you are doing and sends one short, it ricochets out into the parking lot and goes thru a car window. Now people deem the place unsafe and we lose business and the insurance goes up.
If you want to shoot fast why not do it on your own property where you don't have to worry about where the rounds go?