It's also an unnatural situation since if externalities of transportation were priced in (see left part of figure 8.6 on page 610 in https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5...), there's no way in hell that air freight could be cheaper than maritime freight.
If by "trip" you mean passengers, then that's not what I'm talking about. Of course taking care of a passenger for many days as opposed to a few hours would be expensive (large-ish cabin with a bed, food, service crew, recreational facilities etc.). The same passenger survives the flight just in a seat. On the other hand, it's all same to cargo.
All true. And I probably deserve the downvote above. But it’s worth considering factors in favor of airfreight (beyond the increased value of getting your cargo sooner).
Cargo ships and aircraft both require crew, so my above comment applies to that portion of the cost. (Mitigated by the fact that crew per tonne of cargo is typically much smaller on a cargo ship than an aircraft.) Crew also have to be paid.
For a given container, the number of times it can be reused per 10 year lifetime is proportional to the speed of the mode of transport. Airplanes are 20 times faster than cargo ships, so the container can be reused 20 times as many times in a given time period. That means it can be optimized to be lighter, etc. A similar argument applies to the rest of the vehicle. And airplane can make a lot more round trips in its lifetime than a cargo ship. (This is of course mitigated by the fact a ship is usually a LOT cheaper to build per unit dry mass.)
Air travel also can be much closer to destination than cargo ship can. This is mitigated by how efficient intermodal transport is, but some countries don’t even have international container ports and most states don’t. Every city has an airport and usually many of them. This makes it harder for local labor issues to cause massive logistical headaches.
It’s also not that uncommon to lose cargo containers overboard during actual transit in sea, which effectively never happens for air freight (as they use extremely safe airliners with cargo inside the contained fuselage).
Anyway, if we could somehow improve the efficiency of air travel by an order of magnitude and reduce the cost of airframe manufacture, it’s not unreasonable to imagine there may be a way for airfreight to become pretty competitive with sea freight even for cargo that isn’t particularly time sensitive.
