I'm also German. Once, when I was asked for my zip code at checkout, I asked what they use it for. The cashier said it's being used to decide where to distribut

I'm also German. Once, when I was asked for my zip code at checkout, I asked what they use it for. The cashier said it's being used to decide where to distribute physical advertisements (those store-branded magazines that land in your mailbox every week which list all the items that are on sale next week). I can't know how much truth there is to it, so take it with a grain of salt.