You are sort of looking in the wrong place. Free trade and...

You are sort of looking in the wrong place.

Free trade and globalisation is awesome if you live in a big city. Work in financial sector, real estate, multinational comp. admin/management/sales/marketing in offices of large companies.
And many services industries in large cities that pool around abundance of money generated by free trade.

On the other side you have smaller cities and towns that don't have administrative offices, HQs of large multinationals or financial institutions to support service industry around it.
These cities/towns were thriving when large manufacturing hubs were supporting chain of small/medium businesses that were suppliers to manufacturing hubs.
That money supported service industries, real estate, etc around them.
These are the people that voted for Trump. And protectionist policies would greatly benefit them by bringing back well paid jobs instead of unemployment and low wage jobs.

So you have polarized population where people in large city centers have never lived better and people in regional towns never worse.
It's the root cause of Brexit and populist right wing gaining momentum in European regional towns and cities.

So steel tariffs and protectionist policies talk (for now) is all about votes and power.

Hope that makes sense