So from our angle with our SAS troops, it turns out that not only are they doing fucked up things, they're doing them a lot, they're getting more frequent and they're getting more fucked up.
It got to the point that the reason there is a large investigation underway now into our special forces conduct, is that our Commandos (Another Australian branch of special forces dealing with non-secretive warfare) had to step up to the heads of the defence force and the government and say that the SAS is out of control and they need reigning in.
So far we have been hearing of examples of:
Reckless disregard of duty and the well-being of other Australian soldiers.
Targets executed rather than captured for no good reason.
Combatants executed while receiving medical treatments for light wounds.
Targets having their hands cut off (I'm not even joking) post-mortem for verification.
Soldiers mutilating bodies for trophies.
Frequent neutralizing of civilians deemed as spotters with dubious reasoning.
Now the immediate assumption, like you made, is that they see and do fucked up things which is completely right. The other aspect is that we:
Train them to levels of extreme stress to perform their duties
Train them and condition to hold a mentality of becoming and being the best warriors on the planet, including the most bloodthirsty, uncaring and ruthless.
Train them that they're not only the best warriors, but the best in the Australian defence force. That even other soldiers and officers aren't to be trusted (Including other Special Forces units), only their elite, secretive brothers and their handlers.
Shroud their entire personal identity, structure, operations, training, missions, command, health and well-being in complete secrecy. They are separated from the traditional command structure, and as a result their only oversight is from their handlers (Warrant Officers attached to the units).
So effectively in the end we have incredibly highly trained soldiers, conditioned to be ruthless, bloodthirsty and unmerciful warriors, under huge amounts of physical and mental stress, shrouded in complete personal and operational secrecy with no proper oversight to the rest of the military, seeing and engaging in fucked up shit constantly, creating a brotherhood of secrecy and a club of exclusion for dissidents.
And we wonder why they're doing fucked up shit. We've made them this way before they even get onto the battlefield.