If you take charging higher grocery prices for richer people to its furthest point, you could end up with a system where every item costs Y% of their assets and the utility of a dollar is reduced the more you have. In effect, this would eliminate the relative value of having more money. For example, eggs could be priced at 0.02% of total assets, which means a poorer person with $2000 pays 40 cents, and a richer person with $1M pays $200.

Now, would this go to its furthest point? Probably not, but it has the same, but smaller, effect of reducing the utility of money for richer people.

In some scenarios, this actually might make sense. For example, in Finland, they use the day fine system where traffic ticket fines are based on the violator's daily disposable income. It's useful because this is a scenario where you want the punishment to feel equivalent to all income levels.

For groceries, I don't think this should apply, because I think we would not want the act of purchasing food to equally punish all levels of wealth.

This really becomes a philosophical discussion of defining price gouging and immoral market techniques. Some are clearly gouging, such as charging 2x plane fares for someone who has to fly to a funeral, or tripling the price of supplies after a natural disaster. Some are less clear.