Saw that happening recently in a Lidl too. The woman ahead of me in the queue, had absolutely nothing, no basket, and nothing in their hands. Then a man appeared with a basket, and joined her. She had been reserving the space.
If he hadn't appeared by the time the cashier was free, would she have allowed me to go ahead, I wonder. Or would she just stand there like a plonker
...
It's not even a particularly busy Lidl. Well I'm usually in it, in the evening/ night time when it's mostly people with baskets or a handful of goods.