Being charged the same percentage of income is still the same punishment. It’s a non-controversial concept in economics that there is a marginal utility to money, as in, if you have a billion dollars, then getting an extra hundred doesn’t give you more utility. However a struggling family would be thrilled at a hundred bucks and maybe that means eating for the next several days. These people should not be charged with the same static dollar amount.

It seems disingenuous to talk about marginal utility in this context, you're bringing up a non-controversial thing to try to make charging different people different dollar amounts for the same crime also seem non-controversial, which it is certainly not, at least based on the comments here.

You can say it's the same percentage so it's the same punishment, but you can't pretend this isn't a recent change in jurisprudence.