Stephen Sprunk wrote:

And then there's Congress's Internet sales tax moratorium, so the same
product ordered by the same buyer from the same seller may by taxed if
the order was by phone or mail but not if online.

You misstated that. State sales taxes are collected on in-state sales;
there is no federal jurisdiction to impose a moratorium. Use taxes are
levied on interstate sales. These are not collected by the merchant,
but levied directly on the buyer. There's really no federal issue at all,
unless Congress imposes a national sales tax.