There's a company out of Turkey called Teknasyon built entirely around this grift. Some of their apps were bringing in $3 million a month from shady subscriptions before enough "customers" noticed and told Apple. Google runs a very popular search engine that can find more information about this multi-million-dollar scam, but Google also runs a very popular app store still proudly featuring the company's scam products. Let's look at some of them!
Weather Alarms is a lot like the weather app already included on your phone, only it's slower to load and costs $50 a year. Its uselessness is so self-evident that there's no non-insulting way to explain it, so I'll explain it this way: It's like your mother shaving her chest and then signing up for a Chest Wig of the Month Club Ambassador Package. Weather Alarms offers "critical alerts" to paying customers. To a grandpa-brained moron, this language implies all other sources of weather information are keeping snowstorm secrets from you. It also implies this app will very much let a tornado kill you if your credit card expires.
It seems absurd to sign up for this, but it's designed to happen by accident. When you open Weather Alarms, a pop-up leads you to believe you only have two choices -- signing up for a free trial or buying a subscription. However, if you wait, a little "X" will finally appear and let you close the pop-up. It's a cute wink to computer-literate users that says, "Psst! You can't trust us!" To your mother, it's one more blip or bloop happening in the blind spot of her reading glasses as she hits the button without dollar signs on it.