https://news.yahoo.co.jp/articles/fb529335685ed8c2a6385fb40278851eabdc41cc?page=1
Lot of interesting stuff in here, but basically: 1) a mismatch between trainees and host companies, 2) the declining attractiveness of Japan's labor market, and 3) the existence of communities that accept illegal workers.
"When the employer actually meets the trainee, they find that the trainee has tattoos, is lazy, and can't speak Japanese at all. From the Vietnamese's perspective, the agricultural corporation pays an hourly wage, there isn't much work to do, and they can't earn much. The president is abusive, and the rooms are shared.
"Japan is completely defeated by countries like Australia and South Korea in terms of wages. Therefore, market principles mean that the costs of coming to Japan are relatively low. Also, while in other countries you have to take a local language test before starting work, this is not necessary in Japan (for technical intern trainees, with the exception of caregiving positions). In short, anyone can easily become a trainee. The Japanese labor market is seen locally as 'cheap and fast', on a par with beef bowl chains, and high-level talent is flowing to other countries. Recently, people have come to see Japan as not even worth sneaking into, and there has been an increase in cases of people returning home early."
-Basically, Japan's wages are now so low compared to other countries that they can only attract "bottom of the barrel" employees to begin with. And the work conditions are so bad even more obedient and hardworking people wouldn't want to stick around either.
The system is basically exploitative, so it's predictable why many abandon jobs:
The reality of state-sponsored exploitation of foreigners- There has been strong criticism of the Technical Intern Training Program. The government plans to introduce a new framework called the Development and Employment Program from 2027, which will require N5 Japanese proficiency and perhaps allow job transfers after one to two years of work. However, the fundamental problems have not been resolved. "The Technical Intern Training Program brings in foreigners who are restricted in their freedom to change jobs and cannot quit, all in the name of international contribution, into industries and companies where Japanese people do not want to work.
Now that the problems with the Technical Intern Training Program can no longer be hidden, they have decided to change it to a training and employment program, and are honestly saying that its purpose is to 'secure human resources in fields with labor shortages.'" "However, even under the training and employment program, the requirement of N5-level Japanese language proficiency before coming to Japan is to be relaxed so that it will be OK if people take a Japanese-language course after entering the country. Saying 'N5 is not necessary' means that people who have no intention of taking N5 in the first place will enter the country. For now, Japanese society and the Japanese people do not have the capacity to accept large numbers of people who cannot speak Japanese. It is clear that this will lead to more problems."
by jjrs