Interstate mail order used to be untaxed. That was the benefit that offset the extra cost of shipping. You order from the Montgomery Ward warehouse in Illinois

Interstate mail order used to be untaxed. That was the benefit that offset the extra cost of shipping. You order from the Montgomery Ward warehouse in Illinois and ship it to your state tax free. Some states expected voluntary reporting despite federal law clearly indicating they don't have a valid claim on interstate trade. Nobody actually did that. The rise of Amazon led to capitulation and the federal courts have made bad decisions ignoring federal law such that online vendors are expected to collect tax even when the business has no nexus in the destination state.