A family member of mine had a stand off with a Costa employee. The review is still on Google.
It was crazy. She got a drink with cream on top to go. She was at the door or the small Costa and the male barista loudly and aggressively shouted us back. We went thinking maybe a payment issue.
No, he said you can't walk across the shop without a lid as it was a health and safety issue. We pointed out that we had been practically out of the door and that people having drinks in the cafe did not have lids. We were. as you can imagine taken aback by his venom and tone.
My family member refused the lid saying she didn't want the top of her drink to be all squashed.
She almost made it to the door when this man, a good foot taller than her tiny five foot self grabbed the coffee already in her hand.
The thing is she's tiny, but you do not mess. She did not release. So began a coffee tug of war for a drink she had bought and paid for.
With perfect timing, she waited until he gave a really hard tug and just let go. He had cream on him and the floor had coffee split causing the actual health and safety issue he had apparently been so keen to avoid.
She stepped around it back to the till and insisted on a refund. The angry barista took the now half empty cup and threw it so hard into the sink that it splashed all over the walls, fellow baristas etc
He was just an angry bully who saw a chance to have a go at a tiny middle aged lady.
So I don't doubt Costa employees behave badly. I've seen it myself.