> Allow companies to advertise a price exclusive of tax (but inclusive of fees)

But that's what they want -- to advertise the price exclusive of tax.

And some of the fees are the same thing. They depend on different factors and aren't necessarily fixed. You could say that fixed fees have to be included, but that's an obvious loophole; they'll make the fee $5 if you're in California and $4.99 otherwise. Or $5 normally and $0 if you meet some esoteric condition that hardly anybody does, if you require the minimum fee to be included.

> Require companies to list a single total price where the final price the customer pays is less than or equal to. So their advertised price would be inclusive of the highest tax rate the customer would be required to pay.

But then they can't advertise the lower price even if that's what many or most of their customers would actually be paying. Suppose San Francisco has a weird law that would add 300% to the price of the product but only for people who live there, and you're advertising across the entire state.

Also, then they bypass it by advertising a product which is only available to be shipped to addresses in states with no sales tax or expensive regulatory requirements. When you show up and ask for that product they say it isn't available to you but here's one that is which is really the same thing under a different SKU, for the same price exclusive of local taxes and fees.

An advertised price to a purchaser is one thing.

But the collection and remittance of the taxes to the specific taxing authorities is a whole other ballgame. Whether or not you see "$499 + $17 + $12 + $34" or you see "$571" on an item... the 'correct' amounts need to be identified, accounted for and sent to the specific taxing authorities. Doing that well enough, at scale, is not trivial, depending on where you're selling to, and how much.