Why do some jobs take so long to give you an answer after an interview?

I had an interview for a job that I really want to work for and my interview seemed to go really good , the guy told me he would have an answer for me in 3 to 5 days , a few days after the interview I wrote him a Thank you email for taking the time to interview me and that I am very interested in the position, come day 5 I still didn’t hear anything , no email, no phone call , so I called him and asked if any decisions were made and he said he is still waiting for confirmation from corporate , and that he will let me know as soon as he hears’ something. It’s almost going to be 2 weeks without an answer. Why do companies wait this long to make a decision? why post a position and interview for a position , if they can’t make up their fucking minds? I hate this job market with a passion , why do companies make it so complicated for people to land jobs Especially if they need people? He did tell me No news is Good news. Easy for him to say.
Why do some jobs take so long to give you an answer after an interview?
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