Aldi (Süd) and Lidl are in the US. You can look up Lidl's US prices on its website:
https://www.lidl.com/
To see Aldi's prices, you need to use a mobile application called instacart. It lets phones see the prices in-store at Aldi for the purpose of making shopping lists. It also has another set of prices for those that have food delivered or do "curb side pickup". Those are higher than the in-store prices.
If you compare the prices, do you still believe that food is more expensive in the US than in Europe?