I don't think it has to be anything more than inertia. They're a massive company that has millions of lines code running in production for a whole chunk of lang

I don't think it has to be anything more than inertia. They're a massive company that has millions of lines code running in production for a whole chunk of languages. Making a change from python2 to python3 probably seems like more worth than it's worth. It is also a fairly googley problem to think that the way Google does things is automatically superior in all cases. So, since googlers use py2, why shouldn't it be good enough for everyone else?