You can constrain the plane it goes on because there's only a small number of flights between city pairs with a given carrier.
You also can't buy a plane ticket for an anonymous person. It has to be for a legal person, which the government is informed of before the flight takes place. That ID is attached to the luggage when it's checked, which is how they can implement bag retrieval when the passenger doesn't board. I'm sure there's an airline somewhere out there accepting checked bags without tickets or ID, but it's not supposed to be allowed.
For air cargo, someone provides an ID, but it's usually the shipper or some other person with no real involvement beyond working in the supply chain. There's a chain of check boxes that says "I received this from an entity I have a legitimate business relationship with" and that's good enough in practice.