I hate timing chains, the fact they do fail, they do get noisy, the guides and adjusters do wear......yet they have no service intervals.
Now go and listen to the noisy timing chain on a XK engine, any Merc 6, or even a high mileage Rootes 4. They don't have service intervals, because being properly designed and specified, you'll have the engine apart for other reasons well before the timing chain fails.
The reason modern ones fail is because they are longer, tend to be under more strain(higher lift cams, high compression ratios and faster engine speeds), and most importantly look like they were stolen off a 3 year old child's wrist. And that's before you find that some oppswit decided to put the damn thing at the back of the engine, making replacing it when it fails an engine out job. I wouldn't be surprised to find some engineer at BMW has a folder full of reasons why it would be 'better' there than at the front, even though his colleagues should have battered him with it when he suggested the idea.
Older cambelts are similar; Ford's Pinto doesn't suffer much from belt failures as it only drives the cam and oil-pump. Plus changing one takes about 30 mins with no special tools. If only moderns one were as straightforward!