Why do Japanese employees often leave their families behind when they transfer to other towns?

This type of transfer, known as tanshin funin has become increasingly common in recent times for the following reasons:
Families must consider their children's education.
For families who want to send their children to prestigious schools, making a job-motivated move can put the children at a disadvantage.
This is particularly the case when the child attends a school with a good academic reputation in one of the major cities.
Transport is another reason for the increase in tanshin funin.
Japan is a relatively small country with a comprehensive network of air and rail rinks, and unless you are living somewhere very remote it takes only a short time to travel from one place to another.
It is possible therefore to spend the weekend with your family and travel back to the workplace early on Monday morning.