A lot of this goes to money.
Supermarkets hire kids. First of all, kids don't know what they are doing.
Second, they are paid so little and often work hard...and they resent the job. Resentment produces acts of revenge.
So, there is no doubt in my mind that these kids leave refrigerated food out on the loading dock, without putting it away...for hours.
I worked in endless restaurants. Tons of vindictive acts by the waiters toward customers.
Now, if you pay your workers a very good wage and treat them with respect...and, you know, hire someone older than 16...then you do get quality work and service and a staff that isn't motivated to let you get food poisoning because they hate their job.
I remember when supermarkets had staff who were part of unions and made good money...worked in the same place for 20 years.