Lemme Get Something Else, Too
This person decided to pay it forward by helping the lady in front of them in line at Walmart. She didn’t have enough to pay for her purchases, so the OP decided to cover the cost, just because. How very kind of you, stranger! We hope that the universe pays you back for being so charitable.
But their generosity wasn’t enough for the lady who couldn’t afford her groceries. Since someone else was paying for her stuff, she might as well continue shopping and pick up other items, right? That totally makes sense! If we were the OP, we’d let her continue shopping while we exited the front doors without looking back.