I can one up that: I was living in Dubai a few years ago and have a number of photos of fancy cars I could never even dream of affording. If I search for “Lamborghini” or “Rolls Royce” it gives me the photos of those cars. I’ve never tagged them and I’m not an Android user, so they aren’t reading my messages.
All modern gallery apps have some rudimentary photo recognition, but I haven't found any but Google's that will allow you to search terms like "topless/nude" and find accurate results. I would never store photos like that with Google, but I've confirmed it works, and with how many promotions Google has run offering free photo storage with their latest phones there are undoubtedly thousands and thousands of unwitting users who have sensitive photos not just automatically backed up in some Google server, but categorized. Just imagine if these servers were to be hacked and that information was conveniently pre-arranged for extortion.
I understand image recognition searching for generic terms like "cars", but my point is this can even recognise brands. And it only returns photos matching that brand, so it isn't replacing "Rolls Royce" with "cars" to do the search.
I guess it makes sense to do this, given that most things they do is based selling ads, I'm just surprised it is this accurate.
https://imgur.com/caz8D2Y
I even have four photos I took at night, in burst mode, as a Bughatti Veyron zoomed passed, and yes, it can recognise those...