Along with some states charge taxes differently for food products or pharmaceutical products or charge no taxes on some. If you are going to re-sell an item you have a state tax waiver from the state and must pay the tax at final sale to consumer. Quite a headache for an ebay shop having to track state/county tax levels, waivers for resellers, not all items taxable in some areas. Should drive folks back to stores. OR; a niche for a new business model for an intermediary store in a non sales tax state that 'purchases' the item for you for a fee smaller than a tax and it drop ships to you.
Yes, that is a complication. Sales tax may cover one or more or all of the following: non-food items, food, medicines, services, shipping, etc. And all of it could and is called a sales tax.
Big retailers like Amazon and Walmart already do this. They charge me the basic sales tax rate for non-food items and they charge me the food sales tax rate for food items. There’s already software in place to do this. As a former software engineer, writing this would be a piece a cake. Small businesses however would have to buy access to a website or a program to do it for them.