Germany's economic model in the late 19th century, one copied by East Asia, was to force savings into banks, and then give out loans at heavily subsidised rates to well-connected industrialists.
This model has never stopped. Equity markets have never really existed because they are competition with the banking system. And the banks are heavily supported by (or owned) government. They have always paid a rate significantly under market. Always.
Germans have the same median net wealth as Greeks and the highest level of wealth inequality in the world (bar China). This is part of the system. If savers take their money out of banks, it is over (and btw, most German banks are functionally insolvent...they were the biggest buyers in pretty much every meltdown in the past fifteen years).
Germany is a developed economy but it's financial markets/banking system is Chinese (unsurprising because China copied Japan and Japan copied Germany). Savers get utterly screwed, the wealthy are eating their lunch.