What’s missing from these discussions is the idea of competitive advantage. It is inherently more efficient to grow crops in climates where they thrive, tacking a tariff to protect domestic production means intentionally lowering the standard of living of everyone both domestically and abroad to favor some tiny group doing something wasteful.
1. To preserve strategically important domestic industries (historically: food production and mechanization industry)
2. To shield domestic industries while they're growing to take on already efficient and scaled global competitors
Benefiting labor or saving jobs is probably the stupidest use of tariffs, if one of the above isn't also in play, because it'd be more efficient just to offshore it to low COL countries and instead refocus internal labor.
The slippery slope, of course, is that industries will claim to be included in one of the above, but instead sink their tariff-protected excess profitability into shareholder/self-enrichment instead of business investment.
It'd make more sense to require domestic industries in tariff-protected sectors to invest {near tariff} percentages of their revenue in R&D and/or capital expenses (or be heavily taxed).
Otherwise the government is simply artificially inflating their profitability, at the cost of any consumers of the product.
Similarly, military procurement can subsidize relevant industries without impacting the wider economy. In other words you can maintain some domestic steel production etc without impacting the cost of goods.
Without explicitly and financially tying subsidy-fueled gains to modernization efforts, market participants begin to consider the subsidies as business as usual, plan around them, and get lazy.*
It removes a primary incentive to maintain pace with global technology improvements. Domestic industry whispers in politicians' ears that their global competitors are unfair for reasons X, Y, and Z, and they really need more subsidies to protect them.
{Benefit from politically driving new tariffs / subsidies} must never be higher than {benefit from investing in efficiency increases}.
* Lazy as measured by peak international efficiency, not work. E.g. a farmer who works their ass off manually farming is economically inefficient compared to one who mechanizes most of their work
That helps explain why chips, cars, airlines, banking etc get subsidized but PVC pipes don’t.
So all that's happened is an exponential increase in the output volume of sweatshops :/
Pepsi can’t get glass bottles from 3rd world sweatshops at anything competitive with a highly automated factory. In the vast majority of industries it’s just a question of levels of automation and climate control inherently makes automation easier by reducing variability in temperature and humidity. Of course the original distinction around climate control that created the term sweatshops is dying as such operations are largely dying out, but that only reinforces the notion of automation killing off the inherent advantages of unskilled cheap labor.