A good guess for any phone or tablet user, but I’m technical enough to change that default. It was because their results used to be objectively better. It’s also not the default on Windows Edge, and I still remember the experiences just after reinstalling a Windows VM that I’d be confused why search results were suddenly so unreliable until I remembered I was getting bing by default.
Small update: two thirds of my device browsers no longer default to google anymore. I’ll change the rest when relevant.
A guess: because you type queries in the URL bar, and they're the default search engine in your web browser?
(I'm convinced that these days, this is 90% of Google's advantage)
Image search is so hyper-optimised for shopping it's useless.