This is because you have three shipping rules which all apply to US orders. Even though these rules are returning a $0 rate because the product has no weight, the cost of the packaging and your handling is being repeated as the result for each rule. If you trim out some of those rules you won't get this result, and the three rules which are applying are looking up the Priority rate, the Express rate and the Cheapest rate.
The "Cheapest" calculation just compares Priority and Express and returns the lowest of the two, so you do not need rules to also look up Priority and Express, you can safely delete those rules, use the Cheapest calculation to give the best shipping on products with weight, and return the packaging cost on the products which are not being charged by weight.