The funny thing is that "Trader Joe" is the label Aldi uses for their kind of/wannabe US products in Germany, say peanut butter or so.

Aldi kind of invented the simple basic discounter system in Germany. Lidl co-invented/followed them. In Germany customers are very used to it, a few years back Wal Mart retreated from the German marked due to the German customer's behaviour (high quality, low price), they were not able to compete with Aldi, Lidl and the likes.

Myself i have mixed feelings with Aldi, from the discounters it's for some reason the one i like them best. In Germany they have very good suppliers for their own brands e.g. Sweets from "Chateau" which are supplied by Stork (a very good German sweets brand with Toffifee, Merci and Werther's Original).
But it's not only sweets - it's with many products. Some are weak though...

Aldi also played some role in digitalization of the german population: Sales of the Aldi computer and later the aldi laptops were real events. Ppl were actually queuing in front of the stores. Not like these years on Apple shops, but in the nineties Aldi computer sales were very important for students and other folks usually low on cash, but in need of some powerful kit.
Medion is ther tech brand. Today good quality for good prices, but not that revolutionary as in the nineties.

Aldi has a simple slogan which was pretty true for the customer: "Qualität ganz obem Preis ganz unten".

And while I am a customer of Aldi myself I prefer a bit smaller and regional supermarkets. Aldi, Lidl at al are too powerful, too similar. The price pressure for delivery partners is brutal and destroying. Especially meat is way too cheap (the region i live is the home of Europes biggest pork butchery (Tönnies) which is the meat supplier for Aldi/Lidl/Rewe - the low prices are possible becauise farmers don't get adequate prices and personell for slaughtering the animals and processing the meat is casted in Eastern Europe for very low wages with kind of modern slavery work situations... But the meat is cheap, hence ppl buy it. This is not a sane ans sustainabble system.