There were some interesting profiles following the NotPetya attack on Maersk in 2017 where Maersk claimed to have 1,200 - 1,500 applications, 49,000 laptops, 6,200 servers.
Maersk are entering into block-chain "distributed ledger technology" with IBM and similar modern solutions. But one article put $300 of every $2,000 of shipping costs for administration and paperwork[0].
I think you're right, there is a massive advantage to be had, and companies are chasing that advantage. But from my (tangential logistics) background, even the biggest shipping companies have the usual range of legacy systems, heavy administration overhead, plenty of paperwork, excel-based-tools and huge integration headaches.
If you're looking a 20 x 20 x 20 meters of gold (i.e. 8000 cubic meters, not a 20m3 cube) then that's more like 154,000 metric tons.
Which Wolfram Alpha helpfully confirms is approximately equal to the mass of all gold ever mined. There is some contention about this value, the World Gold Council posit 197,576 metric tons (and up to 3000 additional tonnes per year) [1], USGS suggest a cube with 28 meter sides, or 244,000 metric tons [2].
400,000 kg probably comes from 20 cubic meters of gold (386,000 kg).
"In an emergency" has always been allowed reason to leave home during the Victorian lockdowns.
1 - https://www.coronavirus.vic.gov.au/how-we-live