And the vast majority of Japanese are vaccinated anyway because they take health more seriously than we do. If one has covid-19 and needs quarantined, their workplace must allow them to quarantine for the designated amount of days while the sick person is given a care package. Japan has a robust healthcare system and a heavily-collectivist community. If they're even regular sick, they willingly wear masks to protect others from their sickness, not begrudgingly, but for the good of the community. They've worn masks when sick long since before it was cool.

While I don't doubt the Japanese governments intentions behind this, you have to remember that Japanese people view authority in a very different way to many western and European countries. In general you are expected to cooperate with police and state officials in a much more strict way than usual, at least according to those I know who live there. Most people need not be coerced or told to do something if it's made clear that it's in the authority's interest that you do.

Not to say that everyone thinks like that, after all people are individuals who take various values to heart, but still, things are different in other countries.