There's unemployment around the World while Companies and Managers complain about dearth of skilled personnel. Why does this situation arise?

Maybe the main reason is the HR problem or the wrong determination of the current employees's qualifications and experiences .

or for some companies they recruit the wrong employees in the name of relatives inside the company or  intermediaries.

I have attended more than200 interviews board in my professional career. I have seen various problem form employers and employees:

1. Work load analysis and job assessment absent (manpower planning)

2. Recession of business

3. Political instabilty

4. Lack of prfessional skill

5. Lack of product innovation by the owner

6. High competition

7. Use technology

Lack of quality Work force. Sorry to say, there are thousands of Universities / Colleges producing Graduates in Thousands with lack of Practical Field Knowledge and Expertise. I have been interviewing almost100 candidates to select may be1 or2 persons for the job reason being simply this. 

Secondly non-professionalism by many. We apply to every job we see consequently making life of Recruiter more miserable and tough. Many a times due to this those are selected which may not have been a better option for that job

Mr. Amir Mahmoud has put it in simple words. I am of the same opinion.