Why do Google searches return Python 2 docs instead of Python 3 docs?

Usually the Python 2 docs are displayed above the Python 3 docs, but both are displayed. Today, I was searching for "python set operator syntax" and the Python 3 results didn't even show up.

This is incredibly annoying, as 99.9999% of the time I want to see Python 3.6 docs. I'm sure that I've compounded the problem in the past by not reading the actual URL and clicking into Python 2.7 docs, but I've been better at it in the last year or so and I still am overwhelmed with same-title content that leads me to old docs. Any ideas / help?