Earlier quoted context omitted.
Rent is expensive in Berlin for sure, but supermarkets are still way cheaper than Austria
A lot better too. Rewe has ton of options and quality food compared to billa. But I think the supermarkets in germany are better than anywhere else in EU.
That said, I've definitely been to a couple of poor quality Rewes, though most often this is in rural areas or on the outskirts of major cities.
Overall I prefer EDEKA for a few reasons.
Generally I think Germany does well to have a strict two-tier system: there are supermarkets, and then there are "discounters" (lidl, aldi, penny, netto, etc.) and they are very different and have very different aims. The good supermarkets feel free to sell whatever they want because they are not competing in price with the discounters, since most Germans are accustomed to shopping at both lidl and Rewe in the same visit. There is also a third tier, "Bioladen", which often have really good high quality organic food for a reasonable price.
I have to criticise the discounters though, specifically lidl and aldi, they do not give you baskets, only carts, and one of my local lidls had a policy for a few months of not allowing you in the shop unless you had a cart!!
German food shopping is very complex overall, but the quality and range of options is impressive.