Lazy cashier or new policy at Shoprite?

I went to Shoprite King Williams Town, Eastern Cape last week Wednesday to buy 2 items. The cashier named Nozuko Platjies asked me if I need a plastic, I said no. But after paying I realised I have to pass somewhere before going to the car. So I kindly ask her to sell me the plastic. She said NO! Buying a plastic only is not allowed anymore at Shoprite. So I asked even if I just payed for my stuff now, she said yes. I was shocked when did it start? Is it a bitter cashier who is lazy to do her job or is it really a new policy at Shoprite?