Search engines such as Google and Bing are monetized through advertisements — which means that the number of eyeballs that view the results is very important. With nearly 15 percent of phones worldwide using iOS, according to IDC, Apple's default search engines represent a sizable audience, even if those users don't always click through to the respective search pages.
Siri's search powers have reportedly oscillated between Google and Bing through the years. TechCrunch previously reported Siri's deal with Google and noted that Bing will still be used to display Siri searches for images.
Analysts estimate that Google already pays billions to be the default search engine for iPhones and iPads. Investment firm Bernstein has put the figure at $3 billion, even without Siri, after legal documents revealed that Google paid $1 billion to stay on the iPhone in previous years.