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.
I agree with you. Its a fact that Switzerland welcomes not just tourists, but leaders, businessmen and influential people from all over the globe. Its pretty great because all these people may be interested in such advertising and this will promote bitcoin.