Someone selling goods has to abide by some laws - typically, lies/false advertising is prohibited, they might have to provide a warranty, and most contracts can be cancelled within 14 days by returning the goods. This means that the car's specifications will be made available to me, the terms of the deal throughly detailed in a legal document I'd have to sign, and I might get to test drive the car before committing.
Ads in contrast don't have any of this. In your example of articles/poems/songs/funny videos, I don't get to check out the content beforehand, I have no recourse if it turns out to be defective/fraudulent/etc (such as clickbait, or a video with 2 mins actual content and 8 mins filler to get to the 10 min threshold for a second ad) after I "pay" by viewing the ad (and parting with my personal data) and I don't have any recourse either if the advertised product turns out to be a scam or malware.