It's not a matter of cutting corners, you've fundamentally misunderstood the mission parameters of the T-800. It's never their role to convincingly infiltrate human society, whereby some scenario may occur that they'd need to demonstrate they had an anus to gain acceptance. It's their role to reach the designated area, rapidly locate their target and Terminate them as quickly as possible - hence the name 'Terminator', rather than 'Infiltrator'.
They're not hanging around for ages baring their arse at people, its a straight in and out job, the human appearance is merely a superficial disguise so they don't arouse suspicion. Apart that one occasion when its programming malfunctioned, they are NOT glorified anal sex robots or farting mechanical novelties, they are ruthless skilling machines.