It's obvious that the paid-for extended warranties are a bad deal for the typical consumer. The sales mark-up is over 50%, and the insurance company wants a 50+% gross margin. That means the expected pay-out will be well under 20% of the price.
I understand that insurance isn't supposed to be a money-maker for the consumer. It's coverage for a unlikely failures that would be devastating. But the fine print excludes so many types of failures that it's not really providing that protection. Paradoxically they insurance companies benefit from more high-profile failures, since that creates demand without advertising. So really this type of warranty is just taking money with little benefit.
Manufacture's warranties are a much different proposition. They are covering design, fabrication and assembly mistakes. Since these failure happen in groups, they are more likely to be recognized as valid warranty claims and be fixed with little hassle. And since the payout is being made by the same company that made the mistake, it encourages them to fix the problem correctly and do everything economically feasible to avoid the problem in the next model.
Back to the original poster's question: driveline failures in the warranty period are rare. And they cost surprisingly little to fix. While driveline components tend to be expensive at retail, the internal cost is low. Generally they don't take a lot of labor, the time estimate matches the actual time taken, and dealers are paid for that labor at cost (which they don't like at all).
Other failures are much more common, and generate a big proportion of a dealer's profit. Changing a window regulator can bill at two or three hours of labor when it takes half that, and there is a 60+% margin on the part. That's a revenue stream they don't want to give up.