It is possible that Canon is cutting fewer corners than Nikon.
Canon is just overpricing. That's all.
As other posters said, Canon also had issues that they did nor admit.
For example, it took them more than a year to admit the 1D3 focusing issue and provide a fix (which did not work for all, btw).
And the fix for the 'falling 5D mirror' issue was provided after the 5DII was already announced.
To their credit, Canon admitted the 5DII 'black dots' issue right away.
They did the same with the 5DIII 'light leak' issue as well.
The D600 oil/dust issue goes away after a certain number of shots (as shown by LensRentals).
Still, Nikon customers are in their full right to ask Nikon to admit and address the issue.
Overall, both companies have a history of unforeseen issues; no corner cutting.