I accidentally clicked buy premium inside a guitar tuner app the other day, so I quickly pressed the home button. As I pressed it the fingerprint reader started for processing the payment, and bam, I had a $15 monthly subscription to a guitar tuner app.

Luckily the first month was free so I could simply cancel my subscription, but I still don't understand how Apple allows such expensive subscriptions for such silly things. You can buy a real life guitar tuner for less than $15