President Trump is taking exception to the idea that his Administration is offering exceptions to his punishing tariffs. That’s the story after a confusing weekend that offers more lessons in the arbitrary nature of Trump trade policy. Late Friday his own Customs and Border Protection (CBP) department issued a notice listing products that will be exempt from Mr. Trump’s so-called reciprocal tariffs that can run as high as 145% on goods from China. The exclusions apply to smartphones, laptop computers, hard drives, computer processors, servers, memory chips, semiconductor manufacturing equipment, and other electronics. The CBP notice takes the tariff rate...