Why airships, a known failed technology, rather, than, say, a large hydrofoil/catamaran, tech that has been proving quite successful on long distance ferries for decades.
The Hindenberg-class Zeppelins had the theoretical lift capacity of approximately... 8 40ft containers.
Electric cars were failed technology for about a hundred years. But with better battery technology, combined with a need to reduce carbon dioxide emissions, they are the future.
If something can only work effectively at huge scale, there are likely to be a number of enabling technologies needed to get there.
Y Combinator portfolio company Boundary Layer Technologies tried to build a hydrofoil cargo ship to target the market niche that wants to go faster than a regular cargo ship but doesn't need aircraft speeds. The basic technology probably would have worked but I'm skeptical whether the market really exists.
Note that airships gain capacity with the cube of the dimensions. So if you can imagine an airship twice as long, that number increases to 64 40 ft containers. Actually more, since less room is taken up by scaffolding and equipment.
The Hindenberg-class Zeppelins had the theoretical lift capacity of approximately... 8 40ft containers.