For Linda Dearman, the House vote last week to repeal the Affordable Care Act was a welcome relief.

Ms. Dearman, of Bartlett, Ill., voted for President Trump largely because of his contempt for the federal health law. She and her husband, a partner in an engineering firm, buy their own insurance, but late last year they dropped their $1,100-a-month policy and switched to a bare-bones plan that does not meet the law’s requirements. They are counting that the law will be repealed before they owe a penalty.