> One is that they don't use the infrastructure in the state.
This is one way of looking at things, but I think sales tax is much closer to a tax on consumers than on businesses. Or at least is intended as a tax on consumers to fund their state infrastructure, often because imposing an income tax is impossible (e.g. Washington State constitution) or just politically unpalatable.
Normalising taxes is basically impossible in an environment where sales taxes are a meaningful part of a government's budget.
Do the consumers pay the tax to the federal government? No? Then it's not a tax on them, but on the businesses that pay the tax. Business's can choose to charge consumers directly for this, but for online retailers that means additional complexity in the checkout and billing process.
This is one way of looking at things, but I think sales tax is much closer to a tax on consumers than on businesses. Or at least is intended as a tax on consumers to fund their state infrastructure, often because imposing an income tax is impossible (e.g. Washington State constitution) or just politically unpalatable.
Normalising taxes is basically impossible in an environment where sales taxes are a meaningful part of a government's budget.