I don't think you read your own wiki
"Bitcoin has some exposure to fraudulent double-spending when a transaction is first made, with less and less risk as a transaction gains confirmations."
The whole point of balling up transactions into a block is to agree they are not fraudulent. And that agreement doesn't happen for up to half an hour. Thus, the exposure prior to that while not interesting for a cup of coffee is very interesting for $100 worth of liquor or a $1000 handbag or the majority of other point of sale purchases now done with credit cards!
I acknowledged in "DOUBLE SPEND ATTEMPT #3" that double-spending unconfirmed transactions is possible. But if you think you can just send out two transactions at the same time and "trick" vendors into giving you free stuff, you are mistaken (the double spend is visible by the network so you'll look like a thief, and besides, you need a custom double spend app to even attempt this). If you send the double-spend when you leave the store, then the nodes won't propagate it and the miners won't mine it, since those inputs our already spent.
TLDR: Double spends are difficult to attempt but easy to detect.