Which of course they do not. Google uses ECDHE_RSA. DDG uses RSA. ixquick, "the world's most private search engine", uses RSA. Bing does not even offer https.
Google does pin their keys in Chrome though, so they know if there is a MITM (and they have, Chrome's certificate pinning led to DigiNotar's downfall). It's a non-scalable hack, but definitely a good one for the largest search engine and a leading email provider to be able to provide.