That's because they're experienced professionals who have been in the business for a while. They know all models, even Mercedes, have occasional catastrophic failure. It's called a manufacturing defect. It would only surprise them if it became a regular occurrence.
I will guarantee there will be more almost new transmissions failing down the road. Manufacturing defects happen with all mass produced products. It happens to the best of them. And every transmission will fail eventually (with high enough mileage). What I find reassuring is we are not seeing them fail early, like at 70-100,000 miles. I don't recall seeing the failure or even one high mileage CX-5 transmission (auto or manual). That tells me is a very solid design.