When you're a large company of any sort, especially one with a vested interest in how the United States government handles laws pertaining to what you deal in, it pays to have a hand in the political system via lobbying, friends in high places, or both. In Google's case, this goes double; they're trying to get laws passed to allow delivery drones, fully autonomous cars, and all other sorts of technological craziness that will likely require a comprehensive legal framework, and all the while, they have an interest in laws concerning things like business taxes, the internet, and the like. Thus, it would only make sense for Google to get themselves inside the political process as much as possible. According to some emails obtained under the Freedom of Information Act by Campaign For Accountability, that's exactly what Google has done.
Campaign For Accountability is a group that wants as much accountability and transparency in politics as possible. The way they're fighting for that, at least in their latest effort, is by getting together all the documents that they can get their hands on pertaining to the matter, and making them publicly available. The quickest and easiest way to get documents that weren't publicly released but aren't classified is through the Freedom of Information Act. Commonly used for things like obtaining lien information in real estate title work or obtaining permitting history for a business property before beginning work on it, the FOIA system can also be used to obtain just about any government document that isn't classified, up to and including personal communications such as emails.
The emails obtained through the FOIA show a fairly close bond with government officials on all levels, and even White House staffers. In one email, for instance, an informal meeting with a Google exec is arranged when he and staffer David Edelman, whose position is as a "Special Assistant to the President for Economic and Technology Policy at the National Economic Council (NEC)." This is just one of many occasions within the emails where it becomes quite clear that Google's relationship with the White House is closer than people may think, and likely much closer than that of their direct competitors. The full set of messages, numbering in the thousands, is available through the source link, for anybody who may be interested in reading them.