[woodbutcher1963]

You could be correct.
The pizza might be 11” in diameter, instead of 12”. I did not measure it.

It may be a price point. The grocery store says make us pizzas we can retail for $X. Just like Home Depot goes to Moen and says make us a faucet we can sell for $99.

[Dahoser]

Yeah, that's the issue. Despite all the fanfare when unit pricing was introduced way back when as helping consumers be better able to know and compare prices, it's all about shelf price or price point. Do what it takes to hit or remain at that price point—smaller, thinner, fewer, cheaper materials—and you'll be fine. Unit price, shmunit price. It's what the eyeball sees and that's not the unit price.