almost forgotten saw movie question?

Question

why were the bear traps even used 

irl they would not even work unless your some sort of horror super genius and john kramer was super dumb

anyways it does not matter that kramer had no smarts since he was worse than darth vader by a longshot

so why did he not just use a giant mousetrap or something

it also occured to me it was very obvious the cycle trap was a fake for the movie as well and nothing happened to mitch since not even blood of mitch was found after he supposedly got shredded and if not then the camera shifted to the wall

finally the shotgun carosel was really retarded as to who should live and the choice of victim was pretty pathetic no offense

Answer 1

these sounds logical but there were many plot holes in saw