Stickiness of search engines
According to StatCounter, Bing has only 1% market share in the US on phones. But on desktops, Bing has 12% market share. And on tablets, Bing apparently has an astonishing 18% market share. So yeah, that's probably people who receive a Windows device and never bother to change the default search engine. No wonder that Google is paying Apple billions for being the default on iOS. On the other, there's far more than 12% of desktops that are on Windows, so a majority of people do change search engines, and that mostly means Google.