Interestingly thought it's easy to find press releases and related material from the Icelandic government itself which uses Icelandic patronyms as surnames. E.g. [1] from the Icelandic Minstry for Foreign Affairs referring to the foreign minister, Gunnar Bragi Sveinsson as "Mr. Sveinsson".

1. http://eng.utanrikisraduneyti.is/news-and-publications/nr/77...

I wouldn't be surprised if this came from whatever translation office the ministry uses.

It's possible but I think this was probably done to make things simpler for the reader. Often this is to comply with rules. For example in international sports the jerseys will usually have "Einarsson" or "Guðmundsdóttir" on the back which is very confusing. Another example are children who were born outside of the country and had to be given their father's last name (so names like Anna Jónsson exist).

There are also many stories of couples who were not allowed to get a hotel room together because they didn't share a last name.

An ex co-worker of mine had that happen to him. Him and his wife traveled to Austria in the 80s and were having trouble checking into a room in some rural town because it didn't seem as though they were married.

He was able to find an encyclopedia on a bookshelf in the lobby that said something to the effect of "In Iceland women do not take their husband's name when they marry". That resolved that situation.