Why has Sony been recruiting assistants?

There are many assistants in the company and there is a lot of mobility. According to the query boss direct employment display.

1, a large number of temporary assistants are recruited, and few of them can become regular workers.

2, assembly line operation, working long hours is very depressing, as long as there is an opportunity, some people will find another way out, many people leave, so Sony has to keep recruiting assistants.