Crypto-currencies are based on blockchain technology and blockchain technology starts with explicit distrust to the transaction submitted.
It needs a ‘consensus’ - a large group of nodes agreeing that the transaction is valid.
Unfortunately the requirement for consensus limits the number of transactions which can be submitted as every transaction has to be analyzed by every node of the network of nodes of the blockchain.
In contrast the credit card gateways and processors start with explicit trust that a transaction submitted is valid.
The number of credit card processors and gateways is small, and a transaction submitted through one gateway and processed by 1 processor does not need to be analyzed by other gateways and processors.
