You would have been right up to June 21, 2018. After that, you are wrong. See South Dakota v. Wayfair, decided by the Supreme Court on that date [1]. If your business is in the US, and your customer is in the US, you can now be required to collect taxes for your customer's jurisdiction even if you have no connection with that jurisdiction other than online or mail order customers reside therein.

[1] https://en.wikipedia.org/wiki/South_Dakota_v._Wayfair,_Inc.