Yes, you could think that old folks are one of the problems, but the extent seems vastly overrated if you look at the most recent study published by Germany's Federal Reserve Bank: "Payment Behaviour in Germany 2017" (only available in German) [1]. The relevant statistic is on page 52 and shows the forms of payment used grouped by age. The percentages for payment by cash are (2008 percentages in parentheses for comparison):

65+: 58 % (66 %)

55 to 64: 48 % (64 %)

45 to 54: 46 % (52 %)

35 to 44: 38 % (50 %)

25 to 34: 44 % (55 %)

18 to 24: 44 % (69 %)

[1] https://www.bundesbank.de/Redaktion/DE/Downloads/Veroeffentl...