Anecdotal example - I was talking with a (usually very reasonable) friend, and she was convinced Google (via Android) listens to her all the time (with a microphone) and suggests products based on her real life conversations with her friends[1]. What creeped me out was that it was not presented as a conspiracy theory but something completely mundane, almost a remark ("you know how they spy on everyone - like yesterday I was talking about Greece with some friends and today I get plane ticket ads - you know, the usual"). Not even a bit outraged. Crazy for me, but clearly people don't feel about this issue as strongly as we do.
Later her friends agreed that it happens for them too and didn't believe me when I suggested other possibilities.
[1] In reality, most likely ad targeting based on her online habits works as intended.
Test it. Pick a medical condition, randomly. From the musty pages of an old-fashioned book, so there's no digital connection.
Then mention that disease a few times in the presence of your Alexa, Siri, or Google whatever. Talk about the disease to your wife on a phone call once or twice (make sure she's in on it, so she knows never to type the disease into a search engine).
See if you start getting ads for treatment for that disease.
It's a little crazy, but I'm not convinced it's impossible. I've something similar to me happen a couple times, but not under rigorously controlled circumstances, so maybe it was google searches by a relative or friend who overheard me, and I was marketed to by association? Maybe somebody with that disease visited my house and their location was broadcast and linked to my wifi?
I've had many conversations exactly like yours, literally. To reasonable people being convinced that's normal, and me trying to explain how it's probably a coincidence or ad targeting.
Later her friends agreed that it happens for them too and didn't believe me when I suggested other possibilities.
[1] In reality, most likely ad targeting based on her online habits works as intended.