Apple maintains a large database of information on its users, from names and addresses to purchases and many other things, in order to offer the best possible service. However like Amazon, it does not offer very much of that data to its advertisers. As financially beneficial as Apple's advertising platform could be for the company, it does not sacrifice customer satisfaction over offering advertisers full access to its deep database. According to a report from AdAge, major media buyers feel that both Amazon and Apple are having a hard time growing their ad business because of it, adding that they are “slow, cocky and downright stingy” in this regard.
The reports says that Apple doesn't even maintain official sales targets or have a very large sales team. It continues by saying that it just isn't something the company focuses on and that this data would be extremely valuable to advertisers. Both Apple and Amazon have been quoted in the past as saying that ads can at times be disruptive to the customer experience.
Reports say that Apple and Amazon have both loosened up a little bit with advertisers on what data they can access over time, with both having re-launched their respective ad programs several times over the years, but are still significantly more protective than others.
Madison Avenue execs seem to be up in arms with Apple's treatment of its ad partners. But with a large portion of the world's top ad companies all using the platform, its clear Apple's user base of 600 million is just too hard to pass up, regardless of its arguable lack of focus on the business as a whole.