I mean, there are countries where tourists don’t have to pay tax on top of items (meaning they pay for it tax free given if they presented their passport upon purchase proving they’re merely only a visitor, that won’t work on expats though). There are countries who have tax refunds when visitors are leaving (basically reclaiming VAT whilst at the airport), they have already purchased the goods with VAT paid but gets refunded upon them departing.
You can buy stuff from colorado online and not be taxed, like andromeda insights, like if I buy from california there is no sales tax
Online sales tax is charged if the merchant company has a physical location in the state the purchase is being made.