RecentChanges is (besides RandomPages) the only page on Wiki that is updated automatically by the server. (Actually, that might also be the case with QuickChanges, but I don't completely understand that page as of yet).
Why should RecentChanges be an exception? Why don't we have a scripting language so we can make pages like RecentChanges for ourselves, instead of having only one page that is favored by the server?
Any time you EditText on a page, a notification that this happened is added to RecentChanges. If RecentChanges already includes a notification (about the same page), the older notification is deleted.
Note that RecentChanges is not a database query of some sort: it is just like any other WikiPage, editable and textual. It's just that the server takes an interest in adding to the end of it (and in deleting redundant lines).
CategoryWiki CategoryDefinition