Because you don't understand Buddhism. Killing = actively severing living beings with feelings and memories, which includes a self-made (doing it yourself), b teaching others to do it (instigating others to do it), and c seeing the killing and following the joy (being happy to see others kill), which are all considered killing.

Therefore, farming belongs to the industry of indirectly killing living beings, and if you are able to refrain from doing it, you should try not to do it. The Buddhist scriptures have long said that if you have to kill because of livelihood problems (e.g., butcher) or have to do related industries (e.g., farming), then you should recite Buddha's name more, repent more, and return more, and hold a kind heart, and you can also get the blessing.

The most typical case is a butcher in Linzi, Sichuan, because the butcher opposed to his wife to eat fasting and Buddha, every time he killed a pig and forced his wife to press the pig leg, his wife could not bear to be slaughtered every time he pressed the leg of the pig when the pig recited the sutra, so three years after the peacefully show the death of the Western blissful world, the husband witnessed a great deal of touching, and ultimately put down the butcher's knife, to learn the Buddha to do good. Later, this thing spread to Southeast Asia, the Malaysian Buddhist Association funded sponsorship, in accordance with the true story of the film, called "reverse edge", you can Baidu search