It's all down to the huge advances in technology, cut-throat competition from other shipping companies and crew costs, Patagualino..as I am sure you know!
Unmanned commercial vessels are 'not on the horizon' yet, for the reasons you state, plus the unpredictability of the weather and cargoes that are carried.
Imagine an unmanned 'MSC Flaminia' scenario....with the vessel steaming onwards at full speed towards oblivion.
Maybe they will make a movie with a script like that, one day!
Regards, Rick

Yes...All Bog Standard now. No more this bloke or that chap. No more "Sparky" No more people.
Just electronic twins...in case one fails.
Up to which point will you be happy to remove all human beings? Robot ships...Is that your thing?
It can be done & possibly with a reduced accident rate.....
But a robot ship cannot & will not respond to, say, a man overboard...or many other scenarios.
Guess that is not an issue with lovers of such possible vessels & their love of profits.
And that is what this is all about..is it not?
Let us remind ourselves: 2/3rds of the worlds surface is ocean...
We know more about space than our oceans. You profit seekers.....Play these games at your peril.