> is the German postcode not used for transaction validation?
No. The only time I have ever been asked for a post code was when a petrol pump in the US demanded my zip code. I have no idea what it meant, I just put some random zip code for the general area I was in and it was accepted. I've never been asked for my post code in Europe; I can't speak for the whole of Europe though, just UK, Spain, Ireland, Portugal, France, Belgium, Netherlands, Italy, Germany, Poland, Denmark, Sweden, Norway.
It's very interesting to know that postal code verification isn't the global M.O... I've been curious about this for a while and you've provided some valuable context.
FWIW: the pump was asking for the ZIP code of the billing address you have on file with your bank. If I typed in a random ZIP code, my card would get declined. I'm pleasantly surprised someone actually thought to handle the "foreign address" case, even if it's silly that the machine forced you to provide a ZIP code in the first place. That's how low my bar is for payment processing networks, I guess.
No. The only time I have ever been asked for a post code was when a petrol pump in the US demanded my zip code. I have no idea what it meant, I just put some random zip code for the general area I was in and it was accepted. I've never been asked for my post code in Europe; I can't speak for the whole of Europe though, just UK, Spain, Ireland, Portugal, France, Belgium, Netherlands, Italy, Germany, Poland, Denmark, Sweden, Norway.