I’m not aware that Google plagiarized anyone. Unsolicited copying and plagiarism is not the same. Equating unsolicited copying with plagiarism is as wrong as equating shoplifting with setting the shop on fire.
No matter whether you think what Google does with Google Books is right or wrong, equating it to plagiarizing is wrong. I don’t think there are many people who would think that plagiarizing is good; I’d guess even the people at Pirate Bay would not approve of that. And if Google had been found plagiarizing, I’m sure they would not have won any case at court.
I am scientist. As scientist I’m publishing articles. I’ve got no problems with others making copies of my papers. I’d absolutely not be happy with others plagiarizing my work.
Also note that all Free Software licenses, designed explicitly to circumvent copyright for the covered work including derived works, have a clause that the author has to be named. In other words, copying Free Software is explicitly allowed. Plagiarizing isn’t.