Apple has publicly published their response to the FCC's questions about the App Store approval process.
It's a masterful mix of answer and evasion. But there are a few gems in there... including two separate items that together may explain the lousy app review process.
"There are more than 40 full-time trained reviewers, and at least two different reviewers study each application so that the review process is applied uniformly."
"We receive about 8,500 new applications and updates every week..."
8500 updates, each reviewed by two reviewers, means this staff has to conduct 17,000 reviews per week. The exact number of reviewers could be anywhere between 40 and infinity, but let's assume there are 45 (or they would have said "more than 50", right?).
This means each reviewer must review 378 apps per week (with a range of 414 to 347, depending if there are 41 reviewers or 49 that comprise "more than 40").
At that volume, reviewers must review 9.45 apps per hour (assuming a 40 hour work week) ... taking just 6.35 minutes each.
With so little time to review apps, it's no wonder the app store review process is horribly inconsistent, and that developers consistently report uninformative feedback -- or simply none.
Even if every single reviewer worked 80 hours per week at this thankless work, 12.6 minutes per review still is hardly enough time to do a thorough, thoughtful job.
No wonder Apple's app review process is a mess. They have a small staff doing enormous amounts of work with not nearly enough time to do it in.