These are all fake plates and many have actually been used. It is fairly common practice in countries where plates have to be given back to the authorities when the vehicle is de-licensed that people who buy these unlicensed cars for export to their home countries have cheap unofficial plates made so that they have some sort of plate showing on the car when they take it home. Many countries, especially in eastern Europe, will not allow cars without plates on the roads even for a short time but with fake plates from the country of origin, they can drive while they undertake the inspection and registration process.
What the right name is for this type of plate I do not know. I call them ‘fake for export’. They do come up on Ebay from time to time and if you are happy with a used copy or unofficial version of a real plate, then buy it. If you want a genuine, officially issued, used plate then check what a genuine plate looks like before buying anything on Ebay. The website of Francoplaque has an excellent section on each European country so that you can see what a genuine plate looks like.
The Italian example here DP 019 CK is from dj-piero based in France (but selling on Ebay.it) and he claims it is a genuine plate which it most certainly is not. Italian plates are made of aluminium and never of perspex/plexigalass.