Artificial insemination is done with a straw like tube and is inserted into the cervix.
Semen collection is done several ways. Electro-ejaculation with someone holding a catch cup, using a dummy vagina with a collection catch on the end, a teaser animal, gloved hand method is where you would "massage" the prostrate gland.
And I second what some of said, you can't compare human antomy to animal anatomy in this way. And that neutering actually significantly decreases chances of prostrate cancer, eliminates testicular cancer, and decreases chances for infection and spreading it.