Major airlines have credit arrangements with the main fuel companies which are at most airports.
There are some cross-crediting arrangements at airports where there is, perhaps, a monopoly fuel company or a large company is, for some reason, not on the airfield.
Problems do arise, however. Smaller companies (even the size of easyJet and many of the European charter companies) issue their Captains with credit cards in case of diversion to airfields where the companies with whom they have arrangements are not available and cross-crediting with those that are do not exist.
There have been instances where even the credit card has not worked (sorry Sir, we only take Visa, not MasterCard!) or the credit limit has temporarily been reached and the card has been refused.
Most times, an electronic cash transfer has been speedily arranged but there have been three instances in the last ten years reported in the British press where a whip round has had to be made of passengers' cash and credit cards in order to get home in a reasonable time scale.