Business Visa applicants are a minority in any country. For a typical work visa, it's actually unusually simply to immigrate to Japan (all you need is a degree and a job offer). See how easy it is to immigrate to your country with just a degree and a job offer.

Japan just doesn't have a road for unskilled immigration (compared to the US with the green card lottery and all the illegal immigration, EU with all the refugee immigration). They had a program for nurse internship but apparently botched/sabotaged it.