credit/debit transactions are too expensive for these small transactions to be viable. many stores have a „no cards below 10€“ policy because of this.
Credit cards are extremely rare in Europe, and only few places accept them at all, unless they're compatible with standard bank card transactions. Bank card transactions aren't that expensive and used for absolutely everything, including very small transactions.
For recharging your car, there's really no problem at all to rely on standard bank cards.
http://www.eurolabour.org.uk/caps-on-credit-and-debit-card-f...
at least in germany, where OP was trying to charge along the route, there is a minimum transaction fee charged by most payment providers.
However price must be the same for all payment methods.
If there is an administrative fee it also must be the same across payment methods, excluding business cards and Amex/Diners.
https://europa.eu/youreurope/citizens/consumers/shopping/pri...
I only found secondary sources for the direct way, but they state (zahlungsverkehrsfrafen.de) - .3%, at least .08€ for EC tx - 2-4% for CC tx, depending on provider