I think accidental discharge is human error. I did it once with a cartridge rifle. It scared the heck out of me. Another time I took a rifle out of my trunk to discover that I had stored it at home with a round in the chamber. Fortunately I had done as I had been taught and checked the rifle to see if it was loaded when I picked it up.

I guess we could argue all day about safe handling and stupid shooters (me with my AD all those years ago). However, mechanical failures or design flaws are a different story. As consumers, we expect the firearms we buy to be mechanically designed, and correctly manufactured to be safe. The manufactures cannot fully protect stupid people who have AD's like me. But they can make a rifle with safe and repeatable functioning designed and built in.