What if one accomplishes shechitah by means of a mechanism that slaughters the animal - is that shechitah kosher? The answer lies in how much human involvement there is to activate that mechanism. Also, parsing the statements that "all are slaughtered" -- namely, every animal needs proper slaughtering. Plus, how eating meat in the wilderness was not allowed because shechitah wasn't possible, but then, when the Israelites came to the land of Israel, they were able to slaughter and eat the meat of animals. And now (in the time of the Gemara), after exile, shechitah continues instead of returning to the practice of the wilderness. Plus, the dispute between Rabbi Yishmael and Rabbi Akiva with regard to how meat could be made acceptable in the wilderness.