EXPECTING ELDERLY TO CARRY HEAVY GROCERIES

About 3 months ago, I went with my mum and bought bulk groceries at Shoprite Estcourt. My mum is 50+ and the cashier had insisted that my mum must take out each oil (We bought 5*5L) and each rice (2*10kg). I was most infuriated and had asked the cashier why can't you just scan one and multiply by 5. She could not answer me. Hence, the manager was called and I had posed the same question to her. Her response was: It is company policy and whichever Shoprite I go they will do that and I felt that that is BS. Where I reside from all the cashiers do that (They scan once and multiply by the number you got). Seeing that my mum is old and expecting her to that is utter nonsense. The manager was rude and thought just because she is in management she can talk to us anyhow.