I really don't think 20% of Americans have personal shoppers.
Unless you count people whose spouse does all the grocery shopping and manages the finances - I could believe that's a large enough chunk of the population to meaningfully contribute to the 20%
The top 20% would be around $110k or more per year, and there are definitely some parts of the country where $100k will be liveable, but you'll still notice groceries prices going up.