And why do you think this is? Because they don't release concept videos, and they deliver really polished products on their own time. People say Apple is all about marketing, but that's a joke. The press does all of Apple's marketing for them, all Apple needs to do is keep generating hits.
There is a fundamental difference between a shipping product that doesn't meet its sales targets and gets canned and a leaked video of a non-existent product that gets canned before production.
Apple's failed products are more notable because of two facts:
* they release very small number of products
* there have only had a small number of failed products
The tech media does it for them... For free, to boot.