I'm not arguing for unrealistic quality levels, and I will acknowledge immediately that my experience could be atypical.
However, in fairness, if I look at all of the software that I use regularly in a professional capacity today, then it is clearly Google products that are the most buggy, and by a very wide margin.
For example, I have a client who uses Google Docs/Drive. We have rarely managed to hold a meeting without one of our small team struggling to see either a word processor document or a spreadsheet properly, and that's just the minor cosmetic or browser incompatibility bugs that keep appearing along with all those minor UI changes. We have also experienced some much more serious problems, including corruption/data loss and seeing the entire change history for some files become inaccessible for no apparent reason. In other words, it's not just minor UI errors that crept in as the product evolved, there are evidently fundamental flaws in the underlying architecture that don't store the data robustly.
Another example: I spent a couple of days last week trying to figure out why a site that had been working fine for users until recently and had not been changed at all on our side was suddenly generating bug reports. It turned out that recent Chrome builds have broken some HTML5 features in multiple ways. There have been related bug reports in some cases, but they have been closed as the specific example given no longer seemed to be a problem. Again, the nature of the problems makes it obvious that these are not just one-liner issues but fundamental flaws, typically where Chrome is so aggressive with its cache usage and/or trigging redrawing/relayout that it just plain doesn't work. And even though the bugs had been reported, obviously the correct root cause was never identified and fixed.
Another example: I recently spent some time looking into how the Closure Tools are coming along. Have you tried the examples/demonstrations for the Closure Library recently? Many of them simply don't work in Gecko-based browsers, and that would be obvious if anyone working on the project had made even a cursory attempt to test them for five minutes.
I will finish by once again acknowledging that my experiences here may be atypical, and that the particular projects I've mentioned that I happen to be using may not reflect the wider Google culture. But on the evidence before me, I see an organisation that keeps breaking things in its rush to push new features out and that demonstrably lacks robust architectures that keep data safe, effective testing processes before pushing code into production, and proper issue resolution processes when defects do get reported.