I'm not super familiar with Korean culture, but often it's similar to Japanese culture. In Japan government pronouncements are either almost completely followed by people (spirit as well as letter of the law) or completely ignored by people. It's a consensus mentality and if the consensus is formed, then the social pressure to follow along is huge.
In Japan, we've been getting more and more public holidays because people actually take them off (as opposed to their vacation time). We're up to 17 days now. In addition, a few years ago the government insisted that every government worker take 5 days off around Obon (Buddhist holiday usually in August). When I was working at the school, it was taken seriously and people were shipped off even if they wanted to work.
Other things just don't get the consensus. For example, after a fairly recent overwork death, they instituted the idea that every second Friday should end at 3:00 pm. I think that was completely ignored.
As far as effective measure like this, it's not so much crafting a law that describes what should happen, it's more about throwing spaghetti against the wall until it sticks. In other areas, I was around when sexual harassment was an unfortunate, but mostly accepted thing in business. Then one day the government said, "Don't do that" and it just changed over night. It's not like the government had been doing nothing before that, or that the introduced laws were particularly good -- it's just that for whatever reason the society was ready to accept it at that time.
In the context of that kind of culture, I applaud the Korean government's actions. It may or may not have the desired effect today, but if they keep at it, it will probably just improve overnight. Also, the fact that this hits the news is good for other similar cultures like Japan. They see it and the people think, "Maybe we're backwards for following this old way of working". When enough people do that, then it just changes. Very, very, very different than the west.