Earlier quoted context omitted.
Because this is all a political move. This so-called "EU sovereignty" drive is in fact aimed at further reducing sovereignty of the member states via further transfer of power and control to the EU. These digital ID wallets do exactly that. Member states lose control of the ID infrastructure, which will now be controlled by the EU. There isn't much sovereignty left at national level...
Each member state has to implement the system themselves. Where is the loss of control?
(The US constitution originally required federal taxes to be apportioned for exactly that reason.)