Probably a mix of that and the fact that Drive supports a hybrid of traditional folders and tagging that you can't ignore (it would break things) and you can't

Probably a mix of that and the fact that Drive supports a hybrid of traditional folders and tagging that you can't ignore (it would break things) and you can't cleanly implement on Linux (there's no real reliable mechanism to support tags that works on XFS, ext4, and Btrfs, which seems like the bare minimum today you'd need to cover).