[jrochkind1]

I'm not sure. Those backchannels would be enormously more expensive and technically challenging for the commercial entities to do right.

So, yeah, I see your point, but maybe I _would_ rather make it much more expensive to do that, and much harder for them to do it succesfully rather than messing up a technical detail.

On the other hand, I guess eventually they'd get it right in commodity software that everyone can use. Eventually.

Really, I don't know why anyone that wants to do the kind of tracking we're talking about is using cookies anyway, instead of user-agent fingerprints that have been shown to be pretty much unique anyway. So the cookies is perhaps all a distraction. The browser makers don't need to invent a new cookie-less browser fingerprint tracking system, they've already got it with the over-specialized user-agents.