My total monthly expenses have increased by roughly 50-100% since 2006, but that's also because I now earn more, buy more expensive things like steak and good cheese, and am more physically active so eat larger quantities.
I actually think that I overstated food price increase marginally. Many things I buy are the same price they were 15 years ago.
If anything the only huge inflation I ever see is not in consumer goods, but in appreciating assets.
Most people when buying food budget money, not calories. So if food producers shave off a few ounces over time you won't notice because you already buy a surplus of food to begin with. The surplus just shrinks ever so slightly on the consumers end. That unused 2 ounces at the bottom of the mayo jar is now 1. That pack of fruit snacks has 1 less in the pouch, etc.
It usually takes a dramatic sudden change for most consumers to notice "shrinkflation".
I have noticed that when somebody says "so you are saying/suggesting X," X was never actually said/suggested. A frustrating thing to encounter in a discussion. Sorry if I was unclear.
If you could buy all food by weight this would be easier to notice and make an apples to apples comparison. Hat's off to the parent comment if they even tracked it down to the exact amount of food and kept it consistent for years.
Most people set a budget of $X dollars of food that is rather generous and if they get slightly less food they don't notice because they are already buying an excess of calories most of the time.