Am I a customer or a ********

I really don't understand the concept of being in a que to pay for my groceries then be in another que to show the security at the door my recipt to prove that I paid or what I have in the trolley. Pic n pay at protea Glen mall. Why does the Pic n pay at protea Glen mall force me to stand in a second que just to prove to the servirity that I have paid for my groceries. I am used to buying groceries at Pic n pay at Flora center and I am never harassed by a security at the door shouting at me because I didn't stand in a que to show him proof of payment or to prove that I didn't ***** anything. But even the manager at Pic n pay protea Glen confirms that I must prove my innocence before leaving the store with what I paid for, PEOPLE SHOULD START SHOPPING AT STORES THAT WILL NOT TREAT THEM LIKE ********S