This can be difficult to explain. Sales tax or 'Sales and Use tax 'SUT' is the responsibility of the customer not the vendor. I'm an accountant and often a small business will send us a bill that doesn't include sales tax. Some things are exempt from sales tax, but some things are not. It's up to us to decide if we need to 'assess' ourselves sales tax based on the service/product that we received. We send a check to the government for the sales tax the vendor didn't charge us. When we're audited this is one of the big issues that we need to provide documentation. It seems to be a concept that's turned around, but it's up to the customer to make sure the tax is paid, not the vendor. Although it is different state to state. The only way I see Amazon liable for sales tax is through the purchase of their inventory, not the actual sales to customers like us, although it is normally assumed that large corporations charge sales tax and there might be a tax law that says just that. I looked at my last Amazon order and I wasn't charged sales tax, so I'm not sure how Amazon gets around this.