I'll tell you why it's not addressed by the rules. Many times it's impossible to tell if the shooter lights one off accidentally during a draw, or if it was a (really fast) intentional shot. Having the round hit the ground at any distance, 10 feet or otherwise, makes it pretty easy to figure out. But there are a lot of situations where it's actually an ND, but the round impacts the berm or the RO simply doesn't see where it hits the ground because it strikes too far away.
I know a shooter who has a bad habit of doing this exact thing. he's never been DQ'd for it for two reasons. One is that it never hits the ground less than 10 feet away. The second reason is that he plays it off really well, like he was actually just getting his first shot off that fast. Many times, he'll just take the miss on the first target to make it seem like that first shot was intentional. People who shoot with him a lot cringe and roll their eyes when it happens, while people on the squad who don't know him so well all stand there in awe, as if he just busted out the fastest first shot on target from a draw they ever saw.