In my case I've been charged for months, like the poster I have never received any monthly statements or any correspondence at all. The charge description is "Subscribe [numbers] CA" and nothing shows up in Google. I wasn't sure what this was, who the merchant was, or how to contact them.
Now that I've figured out it was this app I installed, but hadn't found a specific use for (and forgot about) I'm poking around again. In the app when I click on "Edit My Profile" it literally says "STEP 2 OF 3" and "Hmm... It seems that you have no set any personal details yet."
I can't remember the original signup flow (I'm confident it wasn't very clear), but even if it was explicit the way ongoing charges work and the value it adds is very dubious.
The poster is not saying that they were charged after cancelling. They say they weren’t aware that it costs $3 a month, which seems pretty obvious from both the signup flow and article IMO
I've been noticing a $3 charge and had no idea this was the source. "Subscribe" is very vague description on the credit card statement. The subscription services I enjoy using have descriptions that show up in Google and send me a statement emailed (or physically mailed) to me each time they make a charge.