It has Do Not Track enabled by default. Safari also blocks third party cookies by default on Mac and iOS.

Are you sure? My Mac has "Ask websites not to track me" set to off and my iOS devices have "Do Not Track" set to off, too. I don't believe I changed them.

I'm probably wrong — I must have enabled mine. I know the third party cookies thing is on by default, so maybe I confused it with Do Not Track.

IIRC during the normal setup flow of either iOS or OSX (not sure which) I remember being asked if I wanted to enable DNT, but I don't think it was enabled by default.