Quoting Wendover Productions:

what makes Japanese railways great  goes far beyond their corporate structure.  

They’re fast, frequent, and reliable, but that’s  part of a virtuous cycle enabled by the success   of the companies. The fact that they are fast,  frequent, and reliable is made possible thanks   to the success of the companies, and the success  of the companies is made possible thanks to the   fact that they’re fast, frequent and reliable. So  if you trace this back to its origin, what truly   made Japanese rail great was the fact that the  Japanese government, and by extension taxpayers,   was willing to invest a tremendous amount of money  into kicking off this virtuous cycle—into building  

a railway network that would go on to grow Japan’s  economy and society for generations to come.