Their only restriction on data collection is that you have to ask them for permission first, and I suspect that's going away after this announcement that Apple are no longer directly involved in approving iAd campaigns. Meanwhile, iAd uses a whole bunch of tracking data including GPS for ad targeting, some of which Apple forbid competing mobile advertising networks from making use of.
Also, I notice they forbid 'messaging that identifies the particular target for the campaign—for example, “Single men, 18–24, who live in Washington State, click here!”.' Presumably because if customers knew just how much Apple were helping advertisers target them, it'd spoil their whole we're-better-than-Google line.
If web ads had followed these guidelines, maybe content blockers would not be so compelling.
[1] PDF: https://developer.apple.com/iad/content-guidelines/iAd_Conte...