I used to call those type job postings, "token interviews". They
already have their candidate but have to post and interview to stay meet hiring guidelines. I used to see job postings with "preferred candidate" stamped on them. A few came up once that was very qualified for so I set up a meeting with the manager of HR. I explained my position and that I thought it was very unfair to be eliminated without a chance to apply. He told me to go back and apply for the job. Bout two weeks later I was asked to come in for an interview. I walked in and he said "you want a job". I replied "yep", and it was done. You have to do some self promotion sometimes or become invisible.