• Did proper random before anybody else
• Active countermeasures against cookie-based retargeting
• Popular enough market that merely having an iPhone in a geographic area doesn't single you out
There's a guy who downloads every page with curl. I see him on web logs. I think he must have some script that parses the amp pages out and does something with it, but because he's the only person in that geographic region who browses the web with curl, he's very easy to spot from a tracking perspective. On the other hand, because he's using curl, I don't think anyone wants to bother trying to show him an ad.