It's to do with group culture issues.
Changing the way things are done in companies is hard because of the preoccupation with consensus, nervousness about standing out, vague feelings that changing practices or throwing out outdated ideas is being rude/unkind about seniors who have been working this way for decades.
The work culture is centered on presenteeism and spending a lot of time hanging out with the group-nobody wants to be the person who leaves the office first. So there is little incentive to speed up work or become more efficient-there is also a tendency to think that spending lots of time on time-consuming work is inherently virtuous or something.
Japan's relative isolation means that there is not much benchmarking with other countries.
Attempts to try and get public schools (for example) to switch to online dashboards and notifications rather than piles of paper coming home have failed, because "Oh dear, there might be one family somewhere who doesn't have a computer or won't learn to use one."
Finally, all Japanese organizations suffer from "silo" tendencies, where people are good at doing their particular job but have little idea what people in other departments are doing.
You can see from this why trying to get systems like teleworking into Japanese companies is hard. People have a hard time dropping the idea that people working from home are "really" working rather than slacking off---they "should" be turning up and hanging out at the company for hours on end. Lots of people have poor computer skills because they have never really been pushed to get any good at them. And teleworking does not work well in organizations where the left hand does not know what the right hand is doing.