Why do you think protectionism works in benefit of the country's people? Ask Brazilians what they think of tariffs and protectionism. Ask for instance how many of them fly to the USA to buy electronics.
I think you need to take tariffs case by case and ask if this an industry worth protecting - do you need to have it domestically, or are you ok to rely on imports? Maybe you want to protect high margin industries supporting good jobs, and are willing to rely on imports for things like clothing, food, electronic assembly. OTOH some things should have strategic importance - so then maybe you want to make sure you (the country) are if possible self-sufficient for things like defense, semiconductor manufacture, etc.
People, just like companies, are most likely to act in their own self-interest rather than in the interest of society as a whole. Sure, you'd like to be able to buy everything as cheap as possible, which in a high cost of living (which translates into high cost of manufacture) country like the US would mean relying mostly on tariff-free imports, and the death of the entire industrial base. Is that really what's best for the country?
