Yes, it's true that our archive does not use the same algorithm as Google. Keywords that you enter must be entirely contained in the recipe themself somewhere (in tags, title, ingredients, etc.)
The feature request you are making here is not trivial to engineer (include plurals, singular, etc. in searches), but there is hope that this will be addressed over the next year. The back-end currently runs on SQL Server 2000. Now, the very latest version of SQL Server, which is called SQL Server 2005, provides for a lot more flexible full text search options, and some time in the next year, we'll have a chance to address this.
In the meantime, from within the software, many of the predefined keywords are available for your selection in the "More Options" dialog, which is available when you click "Find" on the toolbar. Also, note that the search-as-you-type feature will only return the top 10 items -- to do a full search, use the "Find" button on the toolbar, or click the button after you type.
(By the way, many of the comments you're making on the software belong more appropriately in the "Feature Requests" section of the board, thanks.)