I guess you're too young to remember when ALL transactions involved trust. Cheques didn't even have any kind of verification whatsoever, you just handed them out and the shops had to just hope they would clear... if they did not, the payee could obviously get into trouble with the law, but criminals still found creative ways to get away with it... watch the movie "Catch me if you can" to see one of the most entertaining abuses of cheques in history.

Once the transaction goes through your account at the bank (in case of debit) will be overdrawn and the bank will charge a penalty sum/interest as well as asking you to put funds in to get it back to a positive balance again.

Almost all Visa/Mastercard cards support this. It's actually better with chip cards since they're MCUs, capable of storing data including offline 'credit limits' and tabulating how much has been debited offline. Can verify pins offline too.

When you buy food/beer on a plane/train, this is probably happening. Ryanair would rather eat the cost of a fraudulent payment than pay for data and slow down their salespeople.