A little warning, and it is allowed to
It may not be safe enough for the children of a handy person.
My son (When he was 3) solved the problem, of course he had seen me with a screwdriver. The rest of the history is up to your fantasy
It turned out well, but maybe someone may learn of my experience without risking to much.

To the best of my knowledge, these covers are no longer acceptable. They were frequently installed in areas that 'little ones' were the occupants, back in time. The requirement of tamper resistant receptacles within the NEC solved the issues with this type cover, and the few variations of the same type design.

Just curious; the pic is not a device used in Norway, correct?

Right, but we had a similar suystem with our european standard, the main point is that if the child know how to use a screwdriver... its not safe.

These are still sold/used in old circuits with no grounding. (I feel pretty safe without grounding as far as it is no risk of touching any conductive surface that may lead to ground.)

In a new house alloutlets are grounded. (Schuko)