Deutsche Telekom interview questions

The interviewer joined late, then took his own time to get started. This guy has practically the same amount of experience and credentials as I do. Started with bookish questions that I have not been asked ever in my 15 years, probably suitable for a fresh graduate. Asked a few product opinions, that I think I was spot on if one can appreciate the answers. But again these things are subjective. The guy was throughly uninterested throughout. The only spark that came in his demeanour is when he thought I answered something wrong, which lasted till I substantiated the answer. After the starting 10 minutes even I had lost all interest to continue. I understand this guy and the his boss, both have worked in the same company previously and probably are trying to hire more people that they have already worked with. Which is fine by me, can work well for the team. However, why to waste my time with this kind of interview. I could have asked the same questions to him and rejected him. Overall very disappointing interview.