Bruce Schneier may have written the clearest explanation, I have ever heard, of why you can’t ‘trust’ companies like Google and Facebook:
We’re not Google’s customers; we’re Google’s product that they sell to their customers. It’s a three-way relation ship: us, the IT service provider, and the advertiser or data buyer. And as these noncustomer IT relationships proliferate, we’ll see more IT companies treating us as products. If I buy a Dell computer, then I’m obviously a Dell customer; but if I get a Dell computer for free in exchange for access to my life, it’s much less obvious whom I’m entering a business relationship with. Facebook’s continual ratcheting down of user privacy in order to satisfy its actual customers —the advertisers—and enhance its revenue is just a hint of what’s to come.