Do you know by any chance if it was just a local campaign or a national?
I'm pretty sure Zurich and Geneva are the 2 biggest cities in Switzerland anyway. Even if it's just Zurich, that's pretty good exposure, there must be 10's of millions of tourists and other foreigners passing through Zurich every year, many of whom using the trams.
Very few governments support such a kind of promotion on public transport. Though Switzerland is technology adaptive, and has got its own cryptocurrency giving exposure to bitcoin on the main cities grabs good attention from tourists and foreigners travelling to Switzerland. Such a level of promotion need to happen at least on half of the world countries.
That can be a big dream come true if we can see half of all countries of the world giving a good treatment to cryptocurrency, and even if there will just be 20% of them that would be enough to create a sort of snowball for others to get on board. Unfortunately, progress can really be so slow and adoption can be taking time, we can not force people and the governments to come to our viewpoints. We need more time and patience here. One day, I am sure that there will be more and more countries to pattern after Switzerland for that matter.