Google seems to refuse removing because, according to them, "Whole-site removal is ineffective and can easily result in censorship of lawful material."
Instead of removing, they just remove links by request.
Isn't this the same loophole that MegaUpload used? Only removing a link to a file, not the file itself with the claim that other links belonged to potentially lawful owners of the file.
I mean, if the subpoena says "remove a link" you comply with that.
But there's also another fundamental difference: even if there's the expectation of removing all copies of the same exact file, it is "trivial" for MegaUpload to know, by using hashes. They do have access to all files, as it is in their servers.
For Google to delete all pirate links to movie X it would be much more complicated, and would put them on a position of being forced to be the internet police.