My uncle told me a story about when he was deployed to Afghanistan there was a designated area by the mess hall you were supposed to use to ensure your sidearm chamber was clear. Every once in a while, there was an accidental discharge and an officer would be seen over there sheepishly holstering their sidearm. My uncle pointed out that it wasn't required that you had to pull the trigger, just that you had to ensure the chamber was empty. My uncle said he never had a single accidental discharge in the 2 years he was there because he simply never pulled the trigger. If you don't pull the trigger, no bullets come out.

Meanwhile, this happens:

https://www.independent.co.uk/news/world/americas/police-off...

And this:

https://eu.usatoday.com/story/news/investigations/2019/03/19...

So soldiers trained by the US military would sometimes make mistakes with their weapon resulting in a discharge they were not expecting? Seems like perhaps its not so simple a tool after all...

That's like saying a knife isn't a simple tool since chefs sometimes cut themselves despite being trained to use them.