In the app store, Robokiller (anti scam call app) is not flagged as requiring a purchase/subscription. It does.
Look at the Robokiller app in the store listing. If you are looking for a cheap/free app and go through the sign in. It is a waste of time..
To me, this is deceptive advertising. If you want more sales this isn’t the way to sell more subscriptions. I am less likely now to bother looking for a solution in the app store.