Those “extras” are sponsored by the location - in other words Walmart and AMC are paying Ludia money so that players will show up at those locations regularly- because if you are there, you are likely to buy a movie ticket or random stuff from Walmart.
So, if you want extras in Deutschland, you need to send letters to stores there asking them to deal with Ludia and pay for extras, because it will bring customers like you into their stores.
And like the guy said previously the Walmart supply drop is just a regular drop in a different color. (Although I have an inkling suspicion they may have paid to have more rares and epics spawn nearby as well, since I often find more of those levels around Walmart, but I can’t be sure.)
Although missing out on the AMC incubator stinks!! Sorry!!