Aldi DOES NOT own Trader Joe's. However, both stores are owned by the same FAMILY in Germany. But, they're different branches of the same family.
There was an article about this in a business magazine a year or so ago. I'm not trying to bust any chops here, I'm only trying to clarify a common misunderstanding.
Personally, I like Aldi and sing it's praises often. The produce is hit or miss, but when it hits, it really hits. The prices are awesome! I usually shop at Aldi first and then go to Kroger to complete my shopping order.
Also, since I pick up different Aldi stores, I've noticed that stores in nicer neighborhoods have HIGHER prices than stores in the same market, but in lower-income neighborhoods. Prices will be different on staples like milk and eggs. 30 to 50 cents different. This is another unintended consequence of mystery shopping. Without it, I would have never known that different stores in the same chain in the same market would have different prices. I also wouldn't have known that each Kroger store is different in how and when they mark down merchandise.
Back to Aldi, I snap them up at $9 each, but love them when they get bonused to $20!