> Between European bank accounts in the same country. Also, not every European country, unfortunately.

Currently there are 34 countries in the SEPA (Single Euro Payments Area): https://en.wikipedia.org/wiki/Single_Euro_Payments_Area

SEPA rules specify that you cannot charge more for transfers between different countries than you would for a local transfer.

https://europa.eu/youreurope/citizens/consumers/financial-pr...

"If the payment is in euros or Swedish krona, they should not charge you more than they would for a national transaction of the same value in euros.