People in tech thinks that micropayments work. Even if you leave out the drop off in entering card details, it just doesn't work, as if get some payment you are much more liable by law. e.g. Whatsapp is the closes example, which had cost of revenue of $52M for revenue of $10M[1] in the last filing.

[1]: https://www.sec.gov/Archives/edgar/data/1326801/000132680114...