Anti-social forces policy (anti-mob policy) in Japan has been highly effective at cutting off the funding sources of the yakuza to the point that they simply can't recruit anymore:
The meat of Japan's policy is AML/KYC and very actively cutting businesses off from financing if they have ties to the yakuza.
Actual results show that the paper you're referencing is simply incorrect. The paper focuses heavily on how much of the funds are recovered, and how much money is being moved undetected, but doesn't seem to consider how much more would move without enforcement.
https://www.theguardian.com/world/2020/sep/05/making-a-slow-...
The meat of Japan's policy is AML/KYC and very actively cutting businesses off from financing if they have ties to the yakuza.
Actual results show that the paper you're referencing is simply incorrect. The paper focuses heavily on how much of the funds are recovered, and how much money is being moved undetected, but doesn't seem to consider how much more would move without enforcement.