This is specifically an Obama thing. He brow beat the swiss banks to break anonymity. The banks agreed to hand over safe guarded info return for prosecutorial immunity for helping Americans evade taxes.
https://www.usatoday.com/story/news/world/2014/01/22/swiss-banking-secrecy/4390231/
What’s the difference if I put my money in a swiss bank account or a safe deposit box or a PO Box ? how do the owners become liable for my stuff?
These cases are that the US has decided foreign banks must report any accounts held by US citizens.
Most countries caved. The Swiss even caved. Pretty much only the Chinese and Russians told them to pound sand.
This was an Obama propaganda show after Romney was revealed to have offshore accounts.