In the U.S., at least, this is not really true. The FTC has laws that prohibits companies from using non-food products (e.g., glue for milk or motor oil for syrup) in photographs of food they’re selling. They also have laws about deceptive marketing practices. These laws definitely aren’t perfectly enforced, but it’s hardly the widespread problem you’re suggesting it is. Also pretty funny to specifically highlight Chinese food, which has always looked like someone used a disposable camera to hastily snap a photo of a real plate of food about to be given to a customer sometime in 1997 in ~90% of the Chinese restaurants I’ve ever been to.

AI obviously has 0 realness to it. So it’s worse in every way.

In this cases isn’t it that they can use the glue for milk though because they aren’t selling the milk, it’s the cereal (enlarged for texture) that they are selling.