But making copies for yourself, without distributing them, is different than making copies for others. Google is downloading copyrighted content from everywhere online, but they don't redistribute their scraped content.
Even web browsing implies making copies of copyrighted pages, we can't tell the copyright status of a page without loading it, at which point a copy has been made in memory.
Making copies of an original you don't own/didn't obtain legally is not fair use. Also, this type of personal copying doesn't apply to corporations making copies to be distributed among their employees (it might apply to a company making a copy for archival, though).
Even web browsing implies making copies of copyrighted pages, we can't tell the copyright status of a page without loading it, at which point a copy has been made in memory.