On what grounds can we trust a website's privacy policy and how they handle user data?
Taking Google for example which has petabytes of user data, who or what makes sure that they don't misuse user data and endanger personal privacy and is anybody keeping a check?
You can't trust that any data anywhere won't end up as tomorrow's news.
If you have data that absolutely can't be made public, don't store it on a computer.
For anything else, there's always a risk.
FWIW, I trust Google to "not get hacked"; however I assume that they're selling every byte of data that they can make a profit on. This is the price for free access to a level of technology that most of society couldn't afford if they had to pay for it.
There is absolutely nothing that says absolutely whether you can or can't trust a website. There are only degrees of confidence. And these will depend on your activities on that site. Banking will require greater confidence than looking at the weather, for example.
You may trust a large corporate more than a small site. Our you may think the exact opposite. You may decide they all sites hosted in a particular country or by a particular ISP are not good for you. And any site could be bugged or compromised.
In short, there are too many variables to know whether you can trust a site.
That said, if you trust Google or Firefox or Apple, you can gain some confidence through the trust their browsers give to a site, in order to know it hasn't been spoofed. Also, regulatory and audit pressures make compromise more likely to be made public.
