We have very strict customs here as we do not have a lot diseases and pests that other countries have.The first picture I saw was a wooden coffin, oak or some nice wood, with a small emblem on the top. They took it out of the hearse and it only filled the doors about half way up. IMO they then put a wooden casing around the coffin for transportation purposes because when they put it back in the hearse it was much bigger and almost filled the doors. Maybe that is something that is required by the air carrier so that the coffin doesn't get banged up or come open accidently while in flight. I know Australia is pretty sticky about some things. They are the only country I have traveled where the airline had to spray inside the plane for any bugs, etc. before you landed so that nothing foreign was brought to their country.
As you said Fundiva the coffin would have been placed in the crate to protect it when it was strapped down in the cargo hull.