I think it's very far from clear that the Japan Post Bank example is a purely positive story. JPB was for much of its history not subject to the same financial

I think it's very far from clear that the Japan Post Bank example is a purely positive story. JPB was for much of its history not subject to the same financial oversight through the FSA that other banks were; instead benefiting from a laxer regime under a different regulator and then subsequently from a separate supervision office within the FSA. This unusual regulatory position is not limited to oversight. Up until 2011, JPB was not even required to pay into the Japanese deposit insurance system and is allowed to offer higher deposit limits than commercial banks. Japan Post Holdings continues to benefit from a unique position of being allowed to own both a bank (JPB) and an insurance company (JPI). The investment policies of JPB and JPI directly subsidize Japanese government debt (which is ... not a great asset, rated A+ by S&P and on a worsening trajectory of outlook) in preference to performing the fundamental job of banks elsewhere and lending money to private enterprise.