Well Aleksi - that's another interesting interpretation... ;-)

But there is another reason for the "unmanned": In the summer months the ferry is manned every day from June until mid-August by volunteers. During the rest of the year, visitors can travel by operating the ferry themselves. Therefore they have to get a introduction and learn a set of operational rules... So, and when the ferry is now on the other side and will be called, it has to cross the sund unmanned ...
I hope, that additional information was helpful

Kind regards - Marc

More information: https://stromstad.se/trafikochinfrastruktur/linfarjor/linfarjankosterlanken.4.3fed02301498a2c09989bcf.html