Quick answer
The precedent set by the South Dakota v. Wayfair, Inc. Supreme Court Decision allows states to tax remote sales, like those made through Reverb and any other e-commerce sites.
Unlike shopping in-person at a brick and mortar shop where the taxes are based on the seller’s shop location, Marketplace Facilitator Taxes work a bit differently. The tax rate is primarily based on the buyer’s shipping destination, as opposed to the seller’s shop location.
For more information, check out How State Sales Tax Applies to Reverb Orders.