From AppleInsider's "Only 4% of iOS users in US are opting in to ad tracking, report says" posted Friday:
An ongoing analysis of Apple's App Tracking Transparency tool claims 96% of users in the U.S. are opting out of the ad tracking feature which launched in April.
According to Flurry Analytics, which has been tracking daily opt-in and opt-out rates following the launch of iOS 14.5 late last month, roughly 4% of daily users in the U.S. are allowing apps access to their Identifier for Advertisers (IDFA) tag. The figure is based on a sampling of 2.5 million daily mobile active users.
Rates increase when taking other countries into account, with some 11% of 5.3 million daily users opting in to ad tracking worldwide.
Daily rates are calculated by dividing the number of devices that opted in by the total number of devices that both opted in and out using ATT.
My take: Score one for Tim Cook.