Most countries in Europe want the driver's details so that they may be "opened" in their licensing system and attributed a local number so that their offences may be tracked and points deducted from the virtual license. No more points, no more recognition of your foreign license. This is also often wiped after only a year or two as they have no interest to clog up their system with every foreign national with a moving violation.

It is a bit of a dodgy affair when concerning a rental, where there is only one driver permitted. They already have the driver's details since the rental car company provided all of the data. But fighting it would cost 100x paying it. Oh well.