I'm less worried about the idea that people are charged groceries based on income and more worried based on need.

Will the person who buys cigarettes twice a day pay more than the person who pays once a fortnight because it's clear that they require it more? Will the shopper of the family of 6 pay extra because they don't have the time or energy to drive to the next place that offers groceries without this system?

Introducing this based on income seems like a sugarcoating of something far more insidious.