I think money transfer plays a big role. Germany never had a culture of cheques and switched from money to money transfers early on (before WW1), so most stuff in Germany either I pay by money transfer ("Ueberweisung") or a company takes the money from my account ("Bankeinzug") - like mortages, cars, rent, electricity, travelling etc. In the US credit cards partially replaced cheques (and added credit, duh!), which was never something in Germany. The only use of cheques in Germany were traveller cheques when travelling - and then only to get money at the hotel.

Even for the catalog business people payed by invoice and money transfer (and the catalog companies gave you credit).

What is left, like groceries, is often paid in cash.