In the case of MB, this is not a problem because of trying to save a penny here and there like the US carmakers do. It was just an engineering oversight(blunder). Everyone makes mistakes.

Additionally, problems like this are not as pervasive as they seem. I have no idea what the statistics on this are, but if the failure rate were 10% that would be very high. When mechanical products like this have weaknesses, they will show up in certain ways under particular conditions. If the guy at the service department sees 10% of a particular product failing he automatically learns that this is a weak spot and considers this to be a less than robust model, and rightfully so.

Just because you have one of these engines with a statistical weakness it does not mean that yours is bound to fail.

Have a great day,