I agree that the sentence is extreme and should be far shorter, but this isn’t strictly a case of the brakes failing due to bad luck. I live a couple of miles from where this happened and this is a serious hill with MANY signs warning truckers to gear down to save their brakes but I still frequently see trucks with…

You are massively exaggerating. I know plenty of diesel owners (including myself) and none of them have modified their emissions system. This does happen, but it is a small minority.