edit: also, those banks are UK ones. I'm not inclined to open accounts there with Brexit going on. Foreign accounts are also a pain for tax admin.
Yes, the SEPA scheme is old and working only during business days according to the TARGET2 calendar, but you definitely can process a transfer within a couple hours (my online stock broker does).
On another level, why should the state have a list of my accounts at all? It already sees all the accounts at banks within their territory. They don't need to concern themselves with accounts outside their jurisdiction.
In the context of income taxes, it should be enough to report total earnings, regardless of which specific account holds them.