There's a multitude of reasons why review teams do not wish to create an account to test your app. Repeat testing is an obvious one, for clutter avoidance (and close relation, namespace pollution issues), email failures, payment barriers, variations between plans and account types, inadvertent secrets reuse, staff unauthorized to accept any additional T&Cs, simple efficiency, the list goes on.

A prepared account for them is no good either. It could be a special account, makes the app work differently and all their review is for a manipulated test scenario.

Allowing the assumption of malice to overwhelm all other concerns is rarely a wise process. There are other equally easy ways to trigger alternative behaviour. This is why review teams invest in static analysis tooling.

I'm sure they are perfectly capable of signing up. But, I'd bet they are expressly forbidden from doing it.

Signups typically involve agreeing to some terms, and you absolutely don't want company employees working their official job duties agreeing to random T&C's.

So app review is just not going to review the signup flow of an app? It can contain anything and they won't check it?

Are staff allowed to accept terms and conditions for apple?

Why wouldn't the terms and conditions the developer agrees to resolve this problem? i.e. "by submitting this application you grant us a waiver allowing our review team to test your application without agreeing to your terms and conditions"

As I understand it, it's not a signup as such. Account details are stored locally only. It wouldn't make much sense to require signup for an app whose whole point is to be decentralized.

I guess I'd have to operate on the only evidence I have to the contrary: there are thousands of apps with authentication in the Play Store that aren't banned.

I think we all know the drill with walled gardens but if you want a fighting shot of getting in they at least give it their guidelines.

Surely they know. Providing credentials is just part of the standard review process.