Why do many job postings leave "Please say that you saw it in the same city in 58 when contacting me"? What does this mean?

First, because of the website's own needs, let its main customers, that is, recruiters, know that they have the ability of big data. Second, because of the recruiter's own needs, sometimes some industries encounter difficulties in recruiting people, but they can't find talents everywhere. They don't know the browsing habits and data access of candidates, and it is difficult to find suitable talents. Third, because of the applicant's own needs, you need to send your resume to the company, and the company will check your application information or talent resume. I think so.