I work at a bank and it's quite simple really. The systems we use at my workplace are so antiquated and wonky that even giving people read access would be a monumental effort. To put it plainly, modernizing these systems takes effort similar in order of magnitude to landing on the moon. Not for any technical reason, but due to the mountains of manual processes and general cruft built up around them. The EU is not deaf to these concerns, and therefore the laws end up falling short for no other reason than that they want someone to actually be able to follow them.

We are talking about things like "make a request at the wrong time and the system will be broken for the next 24 hours, and you are not allowed to speak to the people who know why".

People (myself included until a few years ago) buy into this "banks need to be secure and move slowly to maintain that" but really most of it is due to mismanagement. The "move slowly" is a rationalization.