Because of the italian constitution (I don't know the spanish one) and its extreme care to shield the juge from the governement.
It was written after the fascist era, you know, by people who had to suffer from a justice by and from the power.
Or so I have read.
It works for the inquiry side, but the judiciary system is much less effective by sanctioning. There, the italian trait of forgiving the culprit is the main factor. Last proof was the calciopoli sentences in appeal.

La répartie est dans l'escalier. Elle revient de suite.