I got food poisoning from sushi before bought from a Korea supermarket. shyt is no joke. It's just not a gamble worth taking. All those joints are packed somewhere else and close to expiry most of the time. If you not getting end of day deals at the actual restaurant that makes them then you gambling.
Ok
Thats your experience
I spent over a decade going back n forth and didn't have any issues (not a big sushi sheep either)
Those stores take care of what kind of food they put out because a lot of people eat them daily. Kids for lunch at schools, workers for breakfast and lunch, bento boxes, musubis, sushi, etc.
7-11 stays busy af at all times of the day overthere. Its stupid to compare gas stations here with 7-11 or Family Marts and I have no clue what random supermarket in korea you went to