I'm thinking it's a way of treating Taiwan more like other countries we deal with, rather than treating them as a part of China.
"Subtitle B – United States-Taiwan Tax Agreement Authorization Act
Because the U.S. is unable to enter into a bilateral tax treaty with Taiwan due to Taiwan’s unique
status, subtitle B provides authorization to the President to negotiate and enter into a U.S.-Taiwan tax agreement that includes provisions generally conforming with those customarily
contained in U.S. tax treaties."