I think there's a few misconceptions here. I've seen a similar setup used before. Your body isn't actually in the tube. There is a shooting bench at one end and the muzzle is in the tube while you sit at the bench. With you outside the tube and the muzzle inside, the sound isn't that bad because it's mostly directed forward.
Yeah, I assumed each pipe will have its own bench and electronic scoring at the other end. It seemed odd to me until someone pointed out the cost factor - just hadn't thought of this as an alternative to a building over 300 feet long. Plus, this many not even require a building permit, per se. Pretty slick - I'd like to go check it out when it's done.