There are barriers to trade besides tarriffs. That's literally the only sensible part of the nonsense justification for the initial values of Liberation Day tarriffs. The E.U., for example, has barriers to trade like food regulations and PDO and such. Protectionism takes forms besides tarriffs. Tarriffs are probably among the least useful, most damaging, most blunt protectionist tools.
Protecting markets is done with tariffs. Are you sure you want to assert that tariffs are good for the economy?