Partially due to WTO restrictions and feigned ignorance. You're right that it's non-trivial to properly assess the P&L of outsourced labor especially when most of the externalities (ex. emissions spreading across East Asia, population health) are not immediately identifiable. Globalization ignores these externalities in favor of short term profit. To put a price tag on such effects would be to acknowledge them, which nobody will do.
Government should stay away from trying to control import/export and see the local labor/business adjust on its own.
In manufacturing garbage in = garbage out. Use shoddy tools, end up with shoddy quality product.
It might work for domestic demand.
But internationally? A guy in India won't care about ethics used behind the product as long as he's getting his welder unit for the price/quality ratio he's aiming for. Usually, the volumes of sales accured in this fashion will result in efficiency beyond what cheap labor/lack of regulations can get.
Have you been paying attention the last couple of years? Every time Trump tried to impose tariffs in order to prop up American manufacturers he faced no end of hostility, endless explanations about why tariffs don’t work, etc.
Hopefully this whole fiasco has opened people’s eyes to the fact that we should try to bring home some amount of domestic manufacturing instead of just saying “those jobs are never coming back” like a certain former president once said.
I've often wondered why import tariffs and/or local manufacturing subsidies aren't used to address this. AFAIK they're set fairly arbitrarily, based on the whims of e.g. President Trump. But imagine if they approximated the difference in cost due to the environmental and labor standards of the two countries. Then it'd be an even playing field; there'd be no advantage in importing from a country with lower standards or exporting to a country with higher standards.
A few possible reasons why not: it seems non-trivial to accurately determine how much labor went into a part (may vary over time and by manufacturer) or how much environmental damage its manufacture caused. And maybe we just don't have the appetite to pay the cost of making things to our alleged standards and would rather dump the environmental cost on China. Even local manufacturers might fight it as they don't like the precedent of considering externalities.