> cheap ice cream is full of air

Every good ice cream is. It has to be, otherwise it would be a block of hard ice, regardless of the quality of ingredients.

You are right, though, in that it could be misleading. In Europe it's generally also sold by volume, but both volume and weight is present on the label, like this: https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2F....