Japan railways are mostly (all?) privately owned.

JR was only privatized in 1987 after the previous state owned railway company borrowed too much to fund its infrastructure projects like high speed rails.

Yes.

From the article:

"Today, the most striking institutional feature of Japanese rail is that it is privately owned by a throng of competing companies." ...

"Core rail operations are profitable for every Japanese private railway company, but they usually only account for a plurality or a small majority of revenue. The rest is contributed by their portfolio of side businesses."

It's like a textbook good application of capitalism that unsurprisingly the US can't seem to get right.

But by companies that care about running railways, not by vultures that want to rip the companies apart and load them up with debt for their own short-term profits.