But now you're exposing the huge problem. It goes from "everybody has to be able to cancel their account in the app" to having to be a contract lawyer steeped in the specifics of every business arrangement and know the law in a hundred different countries to be able to determine if you're allowed to cancel within the app.
Then the app reviewers would either have to be lawyers with plenty of time to make an accurate determination, or they'll be getting it wrong left and right. And it'll obviously be the second one. So now what does the dog kennel owner do, or the OP above, when the app reviewer rejects their excuse?
I also think that the default should be that users should be able to delete their accounts and companies should provide evidence why they have that button disabled or removed.
So in case of review the rule maybe could be: if the user is creating an account in your app, then. the user should have the option to delete their account from the app, unless evidence is provided why the account cannot be deleted because of legal reasons.
If the user is allowed according with their contract or law to delete their account they should be able to request that themselves from within the app. This is what I understand from what Apple is requiring the apps to do. It is very similar with GDPR "Right to erasure"/"right to be forgotten".
For your specific cases:
- if a user rented something then they should not be allowed legally to close their account until they return or pay the equipment. If that is in the contract then the delete my account button should be disabled until their contract is terminated/closed.
- if you're a dog kennel it is the same, the user should keep the account until the dog is returned.
- if you are a parole division of the police and the "customer" by law can have their records deleted they should be able to do so.