Wouldn't the worse problem be that humans are consuming it first? These aren't "animal byproducts" it's food meant to be served to humans in restaurants who ended up discarding it.

In any case, it truly is part of several state laws, including where I grew up, in Minnesota. You wouldn't believe what they feed pigs back there. All kinds of expired foods, pastries, candies, and other convenience store fare. That's what the law is meant to cover, including, "discarded or unused restaurant food."