[tqkxzugoaupvwqr]

Doesn’t answer the question. Rephrased: Why was the patent granted if prior art existed from the 70s?

[DANK_YACHT]

The patent approval process isn't perfect. Had you violated the patent, and had Google sued you, you could always argue prior art. What would your evidence be?

[IshKebab]

As I understand it it's much harder and more expensive to win a prior art claim after a patent has been granted.

[kmeisthax]

The patent office could have just missed the prior art, or more likely is that the claims are more narrow than and represent an improvement upon said prior art.