[himinlomax]

It's not just a tradition but more of a non-starter kind of thing as there is no process or framework in the first place. Countries that extradite their own citizens have jurisprudence, procedures and institutions to that effect.

European arrest warrants are different in that they operate under the idea of European citizenship, and that member countries have compatible and comparable legal frameworks. Also the ultimate authority is with the ECJ and ECHR, same as if the accused was tried locally.

> however, this was for a political issue, so it could have been easily blocked by the executive instead of authorized

As I understand it, the executive typically has the power to decide whether an (actual, international) extradition should go forward or not after the judiciary has decided that someone _can_ be extradited. After all, it's a matter of international relations.

But European arrest warrants are different, precisely because relations between member countries are not a matter of executive power. Instead, that authority lies in European institutions. In this case, either government would have had to refer to the ECJ if they did not agree.