Ryanair should be held accountable for hidden charges they add to their "cheap" flights. From my latest booking:

€0.99 Total Fare
€47.31 Taxes, Fees & Charges
€10.00 Passenger Fee: CC

From a fare of €0.99 that is a 5788% increase on the "total fare" cost.

What exactly are those charges? Why do they vary seemingly randomly? Why I am paying €10 for using a credit card (you don't accept my European debit card); I don't know any other online payment systems which charges €10 to process a credit card transaction.

If I had wanted to take a bag with me (aside from hand luggage)? An additional €30.

If the flights cost €58.30 then that is the cost of the flights, not €0.99. It is blatant false advertising. Stop adding hidden charges and just list the flights at their actual price.