For me, it is difficult to say if Japanese are more stubborn than others. But there is a clear difference in how stubbornness is shown.

Argue with a Brit, or an American, and most of the time they will state their position very clearly. With a Japanese, he/she will listen to you and say "hai" (which literally means yes but within the context can just mean "I heard you" and stick to his/her position.

I think Japanese institutions are more stubborn than individuals :o). "There is no precedence" is a common answer if you have some problem with paperwork and try to sort it out. There is heavy resistance to deviate from accepted rules or viewpoints. This can be both good and bad.

Older people seem less stubborn, though, if you manage to hang around them for a while.

I have no explanation but I agree that the Japanese are quite stubbort. My personal experience that sometimes it is easier to agree to do it their way than to try to persuade them change their mind (but I am talking about my wife obviously :))