The only thing surprising about this is that they are implementing it in the form of an explicit negative interest rate instead of hiding it from the customers

The only thing surprising about this is that they are implementing it in the form of an explicit negative interest rate instead of hiding it from the customers in a per month account fee charge or something like that. Rates have been effectively negative for a while now it's just that in the US the banks have implemented it by piling on fees instead of explicitly charging a negative rate.