Flat lays are quick to set up: a table, even light from overhead and a camera pointed straight down. That makes them the photo most brands already have for every product, often taken on a phone in the stockroom. They show colour, print and outline clearly, which suits folded knitwear, kidswear, accessories and social posts.
What they can't show is fit. A shirt on a table has no shoulders and no fall, so a shopper can't judge length or how the fabric hangs. That's why listings pair the flat lay with a hollow ghost mannequin shot or an on-model image.