Consider the alternative: the laptop you bought on Amazon catches fire and burns down the school of your daughter. The school contacts your insurance, who now has to contact a component supplier in Shenzen (who supplied the power supply), and sue them under Chinese law, instead of Amazon.
1. Proprietary customer information, privacy, just generally not talking.
I look it from outdoor equipment perspective - if on my goretex jacket an YKK zipper fails, for me the jacket manufacturer (say Rab) would be the one to raise a warranty ticket/questions, not japanese YKK which produce billions of zippers for everybody all the time. Although Rab is just buying products from DuPont (sigh...), YKK, threads etc. and putting them together (at least that's a more common situation compared to manufacturing it yourself).
I guess in real world Rab would swallow my specific issue while in warranty and issue a fix/replacement, and if they see enough issues with supplier they raise it in batch mode ie for discount for future or one-time compensation.
As an anecdote on this topic.... I recall having a long necked jacket as a kid where the zipper wore down heavily around the collar since the neck was so long that it ended up being too tall for normal day-wear - and thus a lot of unnecessary stress was put on the zipper mechanism when it was partially zipped up. After a few months the teeth had weakened in that area to the point where the zipper would frequently come off the tracks there. In this specific case fitting a jacket with a four inch collar caused a zipper failure - the zipper was probably cheaply made anyways but if the cut of the jacket had been different there likely wouldn't have been an issue.