That's part of the issue, but Google also automatically extends your search terms with words that it believes are relevant to your search. I will also give certain words a higher relevance based on what ti believes you are really searching for. Unfortunately this often leads to search result pages full of entirely irrelevant results, while pages containing the exact words in your search term are few and far between, if they are shown at all.
This is my biggest gripe with Google's search engine. It used to be that you could specify exactly what you want to get and it would find it for you. Now it thinks it knows what I want better than I do, so it refuses to show me things I know exist and that every other search engine will find with very simple, straight-forward search terms.
