Alan: You're probably right. At least in these instances it was a book of my own and my term selection process included a knowledge of the phrases, as well as the terms, I wanted to emphasize and my search process included an assessment of the term's location as a check on its importance in that place - if unimportant, it wasn't included. Nevertheless, I'm not a professional and only did it because the publisher refused to contribute to funding professional work. (And a co-author and I once paid for a professional index - done by a cooperative [in VA?, can't recall] that the publisher claimed knew our lit - and they obviously didn't... sadly, I didn't have the experience, or oomph, to find folks who'd do a better job.)