Levels of consumer debt in Germany are remarkably low. German aversion to mortgage debt is part of the reason why the country has some of the lowest homeownership rates in the developed world. Just 33% of Germans said they had a credit card back in 2011. And most of those hardly ever get used. In 2013, only 18% of payments in Germany were made via cards, compared to 50% in France and 59% in the UK.
The national preference for cash, then, seems to be the flip side of aversion to debt, which, in turn, can be interpreted as a sign of deep-seated doubt about the future. (German businesspeople are also notorious for their pessimism about the future.) And fear of the future, of course, is rooted in the past.
Source: Why Germans pay cash for almost everything
könnte natürlich auch von einem kulturwissenschaftler stammen, dieser psychologische spagat “mag keine schulden” -> “hat angst vor der zukunft” -> “zahlt lieber cash”