It sounds to me like it is either a knowledge gap of which they may be unaware, or a personality issue. When hiring in the past, I looked for thoughtful, but honest answers-- even if the answer was "I don't know." Someone talking around the question or bullshitting me resulted in a no. Also, interviewers may be sensing some quality which hint that the interviewee would make existing employees' jobs harder. Dunno if this is happening, but things like talking bad about previous jobs, management, etc can turn folks off. Also, if one implies many previous jobs were problems the interviewer may assume that the employee was the issue instead.
I think personality issues are kind of overstated for interviews. Just about every industry has its fair share of jerks and sociopaths that throw people under the bus. Regardless, they have jobs, and almost all of them had to pass interviews to get into their respective companies. These are the workers that set the lower bar for entry into a job, and in the "right" companies, your personality would be passable by those standards to get hired.
