Has been that way since day one of the iOS App Store.
It was because it was re-using the same backend as the iTunes Store which was ultimately backed by an SAP system. One that required billing addresses for all purchases (free app = $0.00 purchase).
As far as I know, no other smartphone app store does this. Apple could have corrected this any time in the past 14 years, but no doubt Apple figured the reduction in expected App Store revenue and decided that it values that revenue more than user privacy.
Well Apple has different App Store regions, so doing this hypothetically allows a company to offer an app for free in one region but with cost in another.
In the US, payments almost always require a billing address for anti-fraud, so people are used to giving it out to pretty much any company that asks for it.
> That was unexpected given the marketing.
An extremely small amount of people will see "privacy" and think "I can use it completely anonymously without any PII being sent".
It was because it was re-using the same backend as the iTunes Store which was ultimately backed by an SAP system. One that required billing addresses for all purchases (free app = $0.00 purchase).