Earlier quoted context omitted.
Individual countries cannot "interpret the directive as they see fit". Transposition has to match the directive, otherwise the whole excercise would be pointless.
Not true. Many of the directives differ in countries (even major ones - for example countries in EU that don't use Euro). EU wants people to believe it is USA but it is not. The directives are not enforceable directly but if you want to be good EU country (which has its benefits) then you need to behave :)
It is possible to lodge a complaint with the Commission if transposition is deemed inadequate (and I'm sure copyright holders would do exactly that), and the Commission may bring a case against the country before the ECJ.
See: https://ec.europa.eu/info/law/law-making-process/applying-eu...