As the owner of streaming media-friendly sites like YouTube, Google has a vested interest in making sure that everyone is able to access their content, no matter what the ISP says. Metered bandwidth has a lot of advantages and disadvantages, the biggest disadvantage of which Google sees as people being limited in their use of high-bandwidth services. Instead, they are vouching for transmission rate caps, in essence limiting the capacity of someone's connection once they have exceeded a certain threshold.
Not a bad idea in theory – it reduces total bandwidth consumption, doesn't prevent users from making use of the Internet 24 hours a day and still (hopefully, as far as Google is concerned) provides a connection suitable for online content. It's an interesting and growing debate that is surely to escalate as streaming services, particularly streaming video, continue to become more popular.