Interesting that our experiences are so utterly different. When I used to raise money for charities I was involved, for a number of years, as ride organiser or tour manager for a number of long distance fundraising bike rides. Bordeaux to Barcelona three times - 120 cyclists on average, Vienna to Prague, 100 cyclists, London to Brussels, 230 cyclists, London to Southend, 3,000 + three times, London to Canterbury, 3,000 +, Lands End to John o' Groats about 7 times, 200 cyclists each time. And we found no difference between the 'average' good quality shop bike and the supermarket and chain brands. Apart from the inevitable punctures most problems came with the expensive ultralight bikes - they were so highly tuned and minimalised that they had problems quite a lot of the time.
Only personal experience of course, as with you, but I think it might say something about the cheaper chain store bought American machines and their European counterparts.
Of course all the new bikes suffered from the 100 mile moment, where cables would reach their stretch and go out of adjustment, bottom brackets would loosen madly - but this is expected on new machines. The thing about buying from a good bike shop over here rather than a supermarket chain is that they tend to build in a free 100 miles service as part of the sale.
Due to necessity I once bought the cheapest bike available from a chain (woman's frame was the cheapest) and immediately went off on a three hundred mile ride - I didn't even have a puncture! I took it home, gave it to a family member, and they rode it happily for two years before a tree fell on it in a storm and bent the frame.
If I had to do it I think I could strip and rebuild a bike blindfolded - as you could too I think, so our experiences are different but both valid, don't you think? :wink: