So who do you think should invest the extra effort into performing searches (aka adding quotations.. or "taking them off"): the hackers with specific, but edge-case search requirements, or the 99% of casual users who just want to learn about "how do helycopters fly"
P.S. I tried both the sqlite and the scapegoat tree searches without the quotes and Google seemed to "know" what I meant... but if you encountered that problem perhaps it's an algorithm that unnecessarily "kicks in" depending on some other circumstances of the search. I would definitely classify this as a problem, but one that should again be easily solved with the use of quotation marks
By the way, the scapegoat tree search query was "scapegoat tree inorder append". Try that and observe 90% AVL tree results on the first page.