Depending on what state you live in, or what state the vendor is in, you'll get it. Hasn't hit here in Fl yet (no state income tax, low state sales tax) but basically it is an issue with many/lots of purchases online so no sales tax unless vendor and buyer are in same state. There have been state laws, court cases, etc.
Been going on for a long time - here's a /. article from '99 when /. was the shiznit -
https://slashdot.org/story/99/12/19/1943230/north-carolina-tries-to-tax-online-purchases