Do you have a source for that? I once asked a captain of a 14.000+ TEU vessel if they really only needed the minimum amount of crew. According to him theory and practice are vastly different. Meaning: a news article explaining that a vessel can be run with X amount of people doesn't mean there are only X amount of people on board.
Secondly, there's all kinds of regulations. A container vessel is operated 24/7. If 7 is the amount of people working on it at a time, in practice the crew will be twice that.
In any case, your response lacks a lot. The person you replied to talked about big boat shipping and how it is not going to be automated any time soon. You only account for the crew on a vessel. There's the customers (loads of which still like to send a fax), lots of outdated governments, outdated vendors, other companies, etc.
The captains I asked was a captain for one of Maersk E-class vessels. They don't use the minimal amount. Unfortunately it's been a few years since I asked and I don't remember much of the details, just that the stated minimal crew is not what's on a vessel.
If a ship has no people, it also needs no bridge, control room, bedrooms, kitchen etc. If it has none of that, it needs to water system, toilets, lighting, heating etc.
And with all that gone, you could fit a lot more cargo on the same size boat.
Can you express "a lot" as a percentage of existing capacity? Because it seems like, relative to the amount of cargo space these ships already have, that percentage would be pretty small.
Related question: if they wanted 5% more capacity in the Emma Maersk, what kept them from just building it that way? Are the sizes of these ships a fuel and utilization efficiency optimization problem?
That's true that newer ships have more automation so crew size reduced dramatically. For example there is no man in machine rooms any more in new ships.
Another thing, crew size would be 3x of needed crew for one shift because in ships there are three shifts, one shift lasts in 8 hours.
