It used to be internet purchases in WA were not sales taxed unless the business had a location in the state. You were supposed to track and report all purchases on your own from out of state sellers (few did). That all changed in 2018, we now pay sales tax on basically all internet purchases.
It's the same here. We are either supposed to report all untaxed purchases or simply tack on a percentage of our income tax.
I'm probably the only person in the state who reports, many people tell me that I'm crazy to do so.