The article is missing one key piece: how are card payments developing over time? My personal experience is that things have changed rapidly over the last years with most larger stores now accepting credit cards and contactless payments are increasingly becoming normal (just months ago cashiers might have looked dumbfounded at you when waving your card over the reader).

It is also critical to note that Germany has some of the lowest prices for groceries. Shops have hence been very slow in offering credit card payments.