Facebook clearly is a public forum. It clearly has shared private data with CA. Both of these issues deserve to be discussed, and both will have different, possibly even conflicting outcomes.

And really, that same thing could be true for, say, cable companies as well - they provide a public service, and they are regulated by a local franchising authority. We don't currently see content regulation, but if your local cable provider started, say, providing a channel dedicated to cannibalism, you might see changes in that. At the same time, the subscriber lists are considered private, and sale of them is regulated.

The main reason you don't see much of a mix here is that pre-Internet communication is mostly of the broadcasting type, which has only very few areas where private data actually exists.