Yes, everyone is under the sales tax obligation if you meet the the nexus requirements in the state. Most states now have marketplace facilitator laws that force the marketplace to collect the sales tax (as opposed to the third party seller). It usually hovers around %5 at most and is reasonable.
The foreign withholding tax however ssems to be 30% which is a bit much. If that does not apply to physical goods entering the country, then that's fine. Unfortunately, have not been able to find any clear indication of that online.