I agree that there is a lack of transparency regarding penalties for spammy pages, but the copyright stuff (and censorship requests by the government) is clearly forced upon them.
At least they release a transparency report about the nature and amount of censorship/copyright removals. (it also shows which party requested the removal, and what exactly was removed)
I am not aware of any other search engine that releases this information.
Just an example: removing certain sites from their autocomplete feature was not forced upon them. They are not required to do this, and they are not transparent about it.
Their transparency is also limited to what is forced upon them, not what they do themselves, quietly and secretly. Also note that other properties, like the massively censored YouTube, are completely omitted from their transparency report (unless it ironically enough involves removing links to YouTube...).
The little bit Google is transparent about when it comes to what they omit from "organizing the world's information and make it universally accessible" (Google's mission statement) is only what suits them.
It's a marketing tool to sell the message "it's not our fault". Transparency and openness are not part of Google's DNA, that bit is just marketing.
It's not the flaws in the system that bother me, this is stuff is hard. It's the marketing-driven pretense of caring and at the same time arrogantly telling us "suckers" to go f* ourselves.
"...It is a partial historical record that includes more than 95% of the volume of copyright removal requests that we have received for Search since July 2011. It does not include..."
http://www.google.com/transparencyreport/
Edit: Here's a list of all removal requests: http://www.google.com/transparencyreport/removals/copyright/...