Well first if tracking and selling data on non-registered users really is that trivial then the issue isn't Facebook it's every website that could be doing this.
Second more importantly privacy seems to be a watchword for tech people. Maybe people claim to care about the sort of privacy you are talking about when asked but their actions speak different. People use Facebook, google maps, leave location data on on their phones. Obviously people don't value privacy as much as they do having access to certain tech. Sad but that's the world, privacy seems to be a thing of the past.
We can all opt out by not using these services. To the extent that we don't there must be some extent to which we accept and consent to this tracking.
I care because I'm afraid of my government and want to keep myself secure from them. I also realize that's not the average person. My preference for privacy means not using Facebook it doesn't mean I get to control how Facebook does business or how people choose to use it.
My view is that ultimately people have to be responsible for the tech that they use and how they use it. We can't just pass along that responsibility to government or business.