This ban is not for singles or bachelors (word used here). It's about workers.
They simply want to keep out the non-customer worker hordes out of the nice places so families and other couples and shoppers can enjoy their shopping.
As much as i also think this is humiliating, i also think there is a good reason behind this ban.
I don't think there is a big difference between friday and other days. They wouldn't let them in anyday. Since they work all other days it looks like the rule applies to fridays only.
People earning 1500-2500QR/month are not their target customers.