Re: True volume of paint in cans
In the case of your ice cream, they can maintain or lower the price by giving you slightly less, but design the container to look almost the "correct" size.
In the case of your paint, there is usually room for a few ounces of tint, depending on size of can.
I have noticed over the years that the volume of most things, regardless of what the product is, is less than it used to be. Soup cans used to be 12 ounces, now they're 10.5. Canning jars used to be true capacity, now they're smaller, anywhere from a few ounces to half a cup.
Part of this is due to the conglomeration of the use of metric and the SAE standard in this country, rather than sticking to one unit of measure. The bigger part is corporate greed of giving less and charging more. Not much you can do but rant about it.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!