I had that happen once, and decided to cancel it as it was a waste of paper (and hard to recycle glossy paper at that). This was surprisingly difficult. It took two phone calls to figure out the third phone number, that would reach a person who could cancel it. I had to threaten to raise the issue with my state representative before they agreed to actually cancel it.

I think those dirt-cheap yearly subscription deals are a US thing. I'm not sure similar deals are common in the rest of the world.

Most ads are bad from the user perspective. Low information enticements rarely perform any useful function. High information discussions, product placement in entertainment, informative websites and tutorials are good, but the vast majority of ads are just terrible races to the bottom.