Bad experience

I went to shoprite naledi ext 2 to buy grocery, I was carrying a lot of plastics to the point of both my hands being over full. In that moment I was forced to stand in the line to exit the store, when I reached the door I was forced to produce a receipt before leaving, this is after standing in line to pay. Why are paying customers still mistreated as if I'm a ********? I was made to stand by the door while they print a receipt in order for me to leave the store, this is so sad because even the workers saw that I paid. Why the hustle of leaving the store like I'm a ********.