I am sure you have seen them on Google +. Google announces this feature or that feature related to Google Drive, and then the rallying call begins, What about Linux, where is Google Drive for Linux".
One such option is Insync, not the boy band, but the Google Drive sync app for Linux. Insync extends Drive's web functionality to your desktop by integrating tightly with Windows, Mac and Linux so you can get work done.
I have used Insync for going on a solid year. I subscribed in beta for $10, since then it has increased to a $15 one time fee that includes multiple devices across multiple platforms. I have used it on countless devices, and as a Linux user, I have a tendency of reformatting my hard drive regularly. It has always been simple getting all synced up again because it was as easy as logging into my Gmail address.
One thing I like about Insync is it allows me to locate the sync anywhere including external drives. On my Linux Mint 17 I have it set up to back up all files to my external SATA drive. Another thing I like is I can choose to have my Google Drive files converted to Libre Office and back again. Another feature I like is the ability to download shared files, not just my personal files, when I sync my Google Drive.
My favorite feature since I am a cloud guy at heart, is I can select not to convert to Libre Office format. What this option does is downloads the .gddoc file which is mainly a link. I have all my files on my external drive for search purposes but when I click on a file it opens directly in Google Drive. I absolutely love this feature.
So no Google has not created a Google Drive sync app for Linux and most likely never will, but Insync is a better app even if they did.