Because politics and money. Let's say the Department of Justice went after a bunch of tomato growers. Word is going to get around among the tomato growers, the companies that buy from them, the companies that distribute them, that these certain politicians are not to receive any campaign contributions. They will hire a lobbyist and go after them. So the politicians do not pressure the department of justice, and the administration does not make it a priority for the department of justice, or any of the organs of government. That's putting aside the cultural, racial, and the American political divide.