Why aren’t Japanese people interested in politics?

During a party, a friend of mine asked me why Japanese are not interested in politics. I didn’t have a proper answer, but the following was my answer I thought in a very short time:

1. General Japanese attitudes: Generally, Japanese are supposed to be very obedient, so it is the same even about politics.
2. The problems Japan has are too complicated to solve just by political ways: Aging society, huge government bonds and so on.
3. The long political ruling by one party: Japan has been a democratic country, but actually it has been ruled by one party for a long time. Even now, there are two major political parties, but the second largest party has a lot of politician from the first largest party. It means there is no difference in political views between them.

They are just my opinions, and we should be more interested in it as our own problems.