There are 4.215 Aldi stores in Germany, 1.997 of those from Aldi Süd who also operates the US stores. Add to that 960 Aldi Süd stores in the UK, 530 in Austria, and a couple more in the other neighboring countries, and I think it's completely fair to be surprised if an aldi price map focuses completely on the US.
There is a big discussion in the EU for some products that are far more expensive in some countries over others. If someone who do this for Aldi in Europe, they would see that some "more expensive" countries, are selling the very same products at lower prices than some of the "more cheap" ones.
And that will piss people off, and politicians everywhere don't liked pissed-off people.
"Aldi" is actually split across two different companies that operate in different regions of the world: Aldi Nord and Aldi Süd. In the US, Aldi Süd operates the Aldi stores, whereas Aldi Nord owns Trader Joe's.
I think the problem there is that Aldi and Trader Joe's stores are in the same territory, should we be looking at localized warfare? :D . I like both, but Trader Joe's is always ridiculously crowded. They could add two more here and still be "crowded" but not "oh-my-god I can't go into that mess". I think they're leaving money laying on the table with this choice. I've lived in 3 cities and it was always the same, too much for those of us who get anxious when every time you stop to pick up something for more than two seconds, you have someone looking over your shoulder at the same thing.
For a long time there was only 1 NYC Trader Joes, in Union Square, and it was a madhouse. Fortunately they do tend to expand, it just takes a while. Off-peak hours like weekday mornings help too.