What bothers me, borrowing from your example of the billboard, is that they don't block your content and make you wait in line. Ads on a video, popups, interstitial, they all slow me down and annoy me.
You could have never have even visited facebook.com and have never had a profile, but still this company was using its cookies to build a profile of you on the internet. All of the articles you read on the internet, the sites you visit, all being collected and tallied by some faceless internet behemoth.
That sort of thing doesn't bother you?
The systematic tacking and profiling of all users of the web is disturbing and I am against it, but honestly, I still prefer Google at the commands rather that any government I can think of. Not that it justify in any way the tracking. It's a dangerous weapon.