Maybe I am wrong, but I have the impression that the European General Data Protection Regulation (GDPR) is contradicting both the principles of the European proposal for Digital Service Tax (DST) and the principles of the strongly pushed blockchain technology. The GDPR requires you, for example, to delete a lot of (personal) data you collect. The DST in contrast requires you to collect a lot of data (e.g. geo-localisation of users) for accounting, record-keeping and other obligations intended to ensure that the DST is effectively paid. The GDPR tries to grant privacy and the right to erasure. The blockchain tries to grant that records are transparent and cannot be changed.
Every function does it’s own thing, that is common. But from time to time some coordination and a consistent overall digital strategy could be useful.