Okay, so the answer isn't really a secret: you work your workers (sometime quite literally) to death. After all, what other country has a word for "death from overwork" (karoshi) and is considering legislation to force workers to take at least five paid work days a year?
It's not that they don't get paid leave, it's that they don't take it. A survey by the Ministry of Labor showed that most worker take less than half their allotted vacation time, and another survey showed that one in six didn't take any at all.
So what will happen if they are forced to take leave? Will productivity fall? My guess is that those workers will work even later than normal on other days to make up for it.
What do you think?