Why does Apple allow scams like Nebula to be on the App Store?

Why does Apple allow the Nebula app to be on the app store after many complaints regarding scams? My cousin got addicted to the app while experiencing a personal crisis and was charged hundreds if not thousands of dollars more than she bought. I saw that some people wrote online that they were charged by Nebula after months of not using it and even after canceling their card.How can I help my relative stay away from apps that are fraudulent like Nebula?