In Germany, Lidl and Aldi do attract higher income brackets as well. It's not considered a freak accident to see a Mercedes/BMW/Maserati/Audi/Tesla parked in front of them. Also small-family diner owners buying there as well, as Aldi/Lidl often beat wholesale prices (Metro Group).
Of course, if you visit one in the red light district it's going to be a different experience.
Lidl seems to have a terrible reputation in the UK and Italy (and possibly elsewhere), but in Germany they're just another discounter.
We do have some more upscale supermarkets, but there's generally little variance in quality among the discounters. Although Lidl does have by far the best store brand (J.D. Gross) chocolate.
The food in Lidl isn't junk quality, most of it is fine. They have some junk quality non-food stuff quite often but there's nothing wrong with the food in my experience.
