Google Fiber works with specific construction partners to preserve the safety and integrity of the Fiber network. If you hired an independent contractor, Google Fiber would have to give them access to proprietary network equipment. Your contractor would need access to the Google Fiber network access points (NAPs) and would need to splice the connected wires. This would be a super high-risk activity, because if your contractor makes a mistake, it could knock out service for your entire block or an even larger area. In addition, your contractor wouldn't be able to troubleshoot any connectivity issues.
We're as excited to give you Google Fiber service as you are to get it. We appreciate your patience and look forward to connecting your home soon.