Brucey
The bike you mentioned was of extremely poor design I think you'll agree and is a rarity these days,as is the Alu Giant someone posted on here some weeks back that had broken in half .
I suspect the vast majority of people don't inspect their bikes for cracks etc,only anoraks like us
,in the same way they don't get under their cars to check stub axles and suspension parts,and whilst I agree,polished and anodised alu parts make inspection/detection easier it's not something I'll lose sleep over worrying about.
The first tandem we owned was a late 80's s/hand Super Galaxy Twin,,it was probably five years old when we bought it.
I had it resprayed and we rode it and toured on it for thousands of miles,no worries,I didn't even consider cracks etc,it was quite noodly and had a 1" threaded steerer.it's most likely still being used.
I've had one frame failure and no cycle parts fail me,perhaps if like a friend of mine I'd broken a few frames and cranksets(in fact he's broken just about everything you can think of)I may be more cautious/wary.
We should also think that some people are a lot stronger than others and a lot rougher/careless with anything they own,which is most likely a contributory factor to failure than anything else.
In the same way some people puncture a lot more than others doing the same sort of mileage,which IMHO is down to the way and where they ride on the same roads,if a rider keeps riding over gravel patches at junctions etc they're bound to pick up something in their tyres sooner or later,similarly so riding 23mm tyres at 120psi on our less than perfect roads puts a lot more stress on a frame,wheels and cycle parts.