Our opponents don't obey the same rules. If you look at the majority of terrorist actions around the world, it seems to work. There's more stress working in Northern Ireland because there's quite a lot of political pressure. People allege there's a shoot to kill policy, but there isn't any. When you get involved in an incident you don't just come back and drink tea.
Weapons go to forensics and they take statements.
Sometimes your hands are bagged so your story is tested against the evidence from forensics. If it doesn't match, you will be prosecuted. On a couple of occasions as an eighteen year old soldier I was confused, but at the end of the day if you're old enough to vote, you should be old enough to fight. It's the army's job to make sure soldiers know what they're doing. It's not as drastic as it sounds.