If corporations are people, and they kill someone, why do they only have to pay a fine and/or possibly elect certain employees to go to prison? I can't poison

If corporations are people, and they kill someone, why do they only have to pay a fine and/or possibly elect certain employees to go to prison? I can't poison a billion+ people like monsanto did and then pay a portion of the profits as restitution. If I poison 1 person I go to jail for life.