I agree there are many reasons why Amazon is successful without tax coming into it. That's one of the reasons I feel Amazon doesn't need the extra advantage of not having the charge sales tax. I realize that making Amazon et al. charge state tax won't level the playing field entirely (or even much at all), but it is one step to equalizing opportunity between physical and virtual retailers.
As has been noted by one or two other commenters, if you buy something from a company such as Amazon, you are actually meant to report it on your state tax return (under USE tax) and pay the tax on it. This regulation would simply keep people honest by charging them upfront.
A few points. I am well aware that prices online are cheaper already before tax. However, when you then add the tax at a brick and mortar store, the price difference is even greater making you even less likely to purchase at a physical location. Making online retailers charge sales tax will bring the difference back to the 10-25% you claim rather than ~20-35% for those states with the highest sales tax
You may fill in you USE tax however, why not just make everyone honest by making sure they pay upfront? Sounds like it wouldn't matter to you either way...
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