Do advertisers not know I already bought the thing they're trying to sell me?

Consider an alternate explanation. The Habit could be in the middle of an advertising campaign and your wife saw or heard some ad for them earlier that day and that gave the idea of getting a milkshake. Also, for other matters, web pages can track how long you keep an ad visible on the page and track your mouse movements too. If you get targeted with advertising about toaster ovens it might be that your mouse was sitting over an ad for one or you just kept a page open for a while that had an ad in it. You never know what websites have access to existing cookies that you’ve allowed so this can all happen out of your sight.

Listening to your conversation and transcribing it takes a lot of battery power. It’s why voice assistants use wake words.

It’s also a lot harder to transcribe a real conversation because people talk over each other so much, not to mention background noise.

Yes, this is definitely possible, and plausible. But still, your phone can be a vector for this sort of information gathering for “targeted marketing”, whether by listening (maybe) or scraping enough data to know when to push a specific ad to you. It’s creepy.

I don’t doubt that is done. I’m just not convinced selling milkshakes is the typical reason. But some guy at the NSA or Google or some other nefarious organization might own shares in a milkshake shack.

Between this, and the new laws about only using cookies to collect data if site visitors actively opt in, it’s certainly harder now (but not impossible). This isn’t an area of deep expertise of mine, but I know that, at my previous agency, we had a lot of conversations with clients about “the cookieless future.”

Very infrequently, if at all. And, certainly not at my current job, where our clients are small-to-midsized businesses, which all have fairly limited ad budgets.

I can top this. I have an online storefront, where I sell 3D printed things I’ve designed (it’s a nice setup; once I upload the designs and set the price, I don’t need to do anything, the company prints on demand whenever there’s an order). For a while there, I was getting ads for literally my own storefront.