And what basis do you have for that comment that they just like to pick on overseas targets? (<-- rethorical question as the answer is known as there is no basis for that at all, that is not what the EU is about at all.)
OBDII is mandatory, and yes both before OBDII (variety of interfaces into the car network) and with OBDII there are ways to change car configurations, nowadays often through car configuration files.
It is pretty open, just not so user friendly for most to start coding and interacting in hexadecimal

That is where third party software makes it easier to do the handshake, and have settings in plain English where you can change configurations. Typically, software like Eutel, or Xtools for generic stuff that not just need to read and clear, but also write. Or brand specific like VCDS for VAG or Carly for BMW or GAP IID for Land Rover/Range Rover, Orbit for Volvo, and so on...
Now it is also possible to read all sorts of details for EVs, and that information is available already on the OBDII bus.