SEPA, PSD2, GDPR etc where only the start. We need more EU and national regulation in the data economy. PSD2 means that there will be standardized access to money data for the application you empower. It was is a huge step towards open data in all sectors.
The same should be the case for accounting data - any application producing PL and BS statements should be able to access and XBRL data (we do this in the Nordic Smart Government project). To make this happen we need ASD - Accounting Service Directive.
And asap also HSD (Healths Service Directive) - and naturally LSD (Logistics Service Directive)...