It's not easy filming the inner lives of human beings. Novelists can go on at length about their protagonist's stream of consciousness (see "Ulysses") while filmmakers cannot show scene after voiced-over scene of that same stream without inducing audience catatonia. See Joseph Strick's misbegotten 1967 film of Joyce's classic for an example.
Trauma -- in the original meaning of the word, not its modern "I'm having a bad-hair day" trivialization -- is among the hardest of inner states to get right in any fictional form, simply because its effects are all but incomprehensible to those who have not experienced it. When a man goes to a war and is still having nightmares about it years later, those who stayed home wonder why he can't get used to it, suck it up, move on. These folks forget the healed cut, the pulled tooth, the discarded lover as though they never existed. They've never faced a horror, a shock, a loss that shredded the core of their beings and rearranged their synapses. They just don't get it and, if they're lucky, never will.
Even so, with the acceleration of trauma-inducing technologies -- everything from weapons of mass destruction to powerful mind-altering drugs -- and the collapse of values that once inhibited their use, trauma has become central to our time. Even in Japan, a society which once seemed dedicated to avoiding conflict at any cost, is no longer immune. Trauma is found in the subways, the schools and the most intimate relationships.