There's plenty of free apps in the App store, that is not the reason. An app you download and immediately asks for a login before showing you anything? You don

There's plenty of free apps in the App store, that is not the reason. An app you download and immediately asks for a login before showing you anything? You don't think that's a bit suspicious? You could just be some shady app harvesting data, why not just ask the user if they would like to sign up for alerts?