Any commercial bank that is not totally useless will be able to give you access to payments, transactions and account statements. There are standards for this,

Any commercial bank that is not totally useless will be able to give you access to payments, transactions and account statements. There are standards for this, for instance ISO 20022 (xml based) or older protocols used in the SWIFT network. The banks will charge a fair amount for this though, and they will do it only for large customer and financial institutions. One reason is that it's one of the thing that they make money from in transactional banking. One other reason is that it's technically challenging, both for a customer and the bank to set up a secure message interchange, and there is no standard for authenticating the messages, or the sender.(That I know of, that's reasonably sane.) One other reason is that it's normally a lot of manual work to set up all this for a customer. It's also expensive to devlop a solution for this. There are a lot of systems that handles different things - ledgers, payment systems, message brokers, authorisation systems, the actual internet banking system, etc. In any case, it's more than one system and it's complex.