At least in Berlin, the influx of other european citizens did have a significant effect on the rents. I cba to find sources in English, but the city is trendy, and locals are annoyed by the masses of young hipsters who come live there, making rents rise, and don't even bother to learn german/integrate the slightest. There were for example articles about berliners who were flabberghasted that some bars and restaurants couldn't take orders in german.
OTOH, native German speakers easily get frustrated very easily and switch into English, if you're holding them up at a shop etc.
The bars that don't take orders in English don't actually refuse to do that out of some principle but just because there are just not enough German speaking baristas or bartenders or the market.
For most business owners that is fine because this is a common scenario just in the trendy hoods where most of their customers are anyways English-only speakers.
It would follow mathematically from the pidgeonhole principle, right?