Your first sentence might in fact be true, but you've presented no evidence or argument that it is, so all you've done so far is make a cheap dig at America's private-equity industry with nothing to back it up.

I fail to see how the topic of this comment thread (namely "why Japan has such good railways") sheds any light on the US PE industry or vice versa. Maybe you can explain the link. (If you can't then your cheap dig is also off-topic.)

(And I fail to see how antitrust law in particular might constrain a PE firm in any way.)