But checking in in-person is €0 only if there's more than 2 hours left until the planned departure, it is €55 if there is less. So in practice, a lot of people end up paying €75 for something that's free when flying with other airlines.
In Ryanair's defence, they explain it on their site. But if you are booking via e.g. Kiwi.com, you will probably never visit Ryanair's site and you will miss this detail.