I mean, you can put a real phone in a box and film it but it's not foolproof as you can just open the box again and ship something else. it's not an easy problem to solve. especially with different jurisdictions in different countries.

Even if you had a film of the box being delivered to the post office you could have a corrupt post office friend or a post office worker that is scamming things on their end by opening packages and replacing the contents.