Why you never hear back after applying for a job ?

Demand & Supply.

Supply is more, demand is less.

So, employers have an upper hand.

ONE JOB &1000 APPLICATIONS ,,,,,,,,,,,,,,,, SO DO NOT EXPECT MUCH AFTER APPLYING ,,,  RELY ON YOUR LUCK AFTER SENDING THE APPLICATION...............   PRAYERS ARE THE BEST MEDICINE AFTER DOING THIS ................ GOOD LUCK

Supply and demand yes, with a mechanism of decision making that's not so clear.

Thats because first preference is given to local nationals.

Agreed with Mr. Zafar, just because of unlimited applications for a single job post...

Its , just demand & supply. We who are candidates are many who apply-either the vacancy gets filled by getting the right candidate before reading our applicants (or) we are not fit for the job applied & targeting wrong (or) we are demanding / expecting higher than what we could get as per our value in the job market -may be we are not worth what we are asking for - So, redesign your CV accordingly if we are on a wrong footing . For, every answer we cannot blame our luck . Luck plays a role but only if we try . If we put our best & blame luck / time ( samay ) and finally god . He has not send us for this & neither he has time for all of us. He has left us to swim our own style & go back . How pure we go he is seeing . Otherwise , he has left us to work in this material world . I do not believe in spoon feeding . I would like a person to be thrown to a swimming pool straight after his/her birth-so that its a indication by parents - by society - swim & get used to it dear .

Because HR is racist, specially the middle east one.

It means that you have not been shortlisted for that job. Your job is to apply for the vacancies. Do it with sincerity and keep searching for the next one. 

Nice elaborative answers by the professionals............ I support the question of Bhoraj .......... and want to add only one point..........

Atleast some of the companies (particularly who claim themselves as professionals) should reply to the applicant with a NO or a regret letter............ via email. i am sure it wouldn't take much time of them.

Dear Bhojraj.

There are many reasons behind it. Our colleagues mentioned about some of them.

The unemployment problem is mainly because of lack of guidance from the younger age. At home, At school, from the society and after all lack of direction by the Government(s).

If Bhojaraj is starting a company, how many candidates you can accommodate? And what will be your selection criteria?     ----this is the fact--- the field is survival of the fittest: Both in direct ways and also .....

Perhaps lack of professionalism in the recruiting system.

Unfortunately, many recruiters are only interested in finding the right candidate. They do't care about irrelevant candidates, that's why they wont take the time to send a regret letter, even if it is a cut-and-paste issue.