I do think that is low which makes me question NerdWallet’s value as a tool. Outdated perhaps? This link shows a national average of $3.26 although Louisville is super low. I feel like I live in an area with decently low food prices and my local chain’s store brand is $2.59 right now.
https://www.ams.usda.gov/sites/default/files/media/RetailMilkPrices2019.pdf