On my last trip to Germany my credit cards (chip-based Visa and MasterCard) were declined more than usual. I've been there like 10 times and haven't noticed this before but on this trip train ticket machines refused to service them, small shops didn't accept them and even a huge consumer electronics network store Mediamarkt said "EC cards only". (Whatever "EC card" is)
Has anything changed in regard to credit cards in Germany in recent years or was I just unlucky this time? And what's the root of this problem? As far as I understand these chip-based credit cards technically are not that different (if at all) from debit/atm cards.