One, the military will not pay for anything more than the cheap foam earplugs that you have to roll and squish to get into your ears. It's unrealistic to think soldiers can pay for the hi-tech mini electronics as the lower ranks still dont get paid very much.
Larger hearing muffs would never work for us as we need to be able to get a radio mic to our ear to call for air support or whatever else we need.
I'm not saying your ears won't hurt after the indoor shots, but i'll gladly take ringing in my ears over a dead family. Unless you have the muffs you just don't have the time to squish the other ones in your ears.
The size of the room, and the type of walls makes a difference when shooting inside.
This is another topic where people can argue both ways for days and days and never really get anywhere. Shooting inside was not the worst thing I've experienced in my life, and sure it does suck to have to do it, but I won't be rushing to get my plugs in when my door get kicked open anytime soon.