I don't think most average web users do a comparison of browsers. They pick one (or get told to use one) and stick with it because for their use cases, there isn't much differences between the browser anyway.
They probably aren't keen observers, but if the browser is slow or confusing and they get annoyed, maybe they wouldn't install it next time? It's not like people are completely oblivious to quality.
But we're just comparing impressions and I'd bet there is better data out there.
