Earlier quoted context omitted.
It's also the stark differences in the consequences of misuse. Google can use my information to serve me diabolically targeted ads. The government can put me in jail. It's not that I trust Google more, it's that they have vastly less power to harm me even if their intentions are bad.
The difference is quite subtle, if any. I'm not even sure why you are afraid of government stalking. After all, government is prevented by the rule of law from arbitrarily throw you in jail. For every reason you are afraid of government, you should be afraid of corporation X. Furthermore, there is no guarantee that corporation X will not collude with the government to do you harm 10 years from now. These corporations…
In the uk and the us at least this is no longer true. I they call you a terrorist (with or without proof) the normal laws don't apply. They are also collecting everything we do and storing it for as long as technically possible, quite soon that will be forever.
Government agencies are the bigger problem at the present moment in time, not corporations.