It's suggested in the first article that the pilot had failed to pass the necessary exams:
"The other side of the story here is that the pilot has spent the past six years completing a two year training course, and still hasn’t passed any of the tests necessary to become a pilot. The airline became fed up, and since they’re firing pilots anyway and trying to cut costs, they also decided to terminate their contract with her at this point."
Interviews and tests don't determine how competent someone is going to be performing a job in future, passing candidates are just as likelty to be as competent or non competent. What you should really be asking is that how come they end up hiring competent people in first place? Because those who apply are already have knowledge or experience to help them be competent in first place. I have seen some people who interview and pass tests well end up being useless and sometimes those who initially don't present well end up being competent. How would you determine competency in the first place? In many cases with enough practice and assistance even the most incompetent can perform the required tasks successfully. There is no test to show that anyone is going to be competent or not in future. At above some intelligence level everyone is just as likely to end up being competent in performing any job, but the time that they have reached the position of applying for a specialised job they are likely to be competent in.