I would say part of this can be chalked up to a cultural difference. Germans and Japanese are risk-averse (as a generalization) and don't like risky entrepreneurial ventures. You want to take a nice business plan to a bank for debt financing, instead. Think of all the big public German companies like SAP, Bayer, Siemens: they're all in boring, bog-standard industries.

In contrast, other cultures with a greater threshold for risk have more of an appetite for the stock market. This goes hand-in-hand with innovation/startup culture.