Yet if the whole environmental factor of shipping/transportation and production emission standards are factored in - those cheap imports would become less cheap

Yet if the whole environmental factor of shipping/transportation and production emission standards are factored in - those cheap imports would become less cheap and negate the need to allow some local production to almost die before noticing that it's unfairly suffering due to it having to comply with a higher level of environmental and worker standards compared to some import. Hence you get workarounds happening like the example you mention about chicken tax - https://en.wikipedia.org/wiki/Chicken_tax https://en.wikipedia.org/wiki/Chicken_tax workaround that can play both ways, yet if there was a base-level standard and measure to balance things out, then such loopholes become less harder to happen, or needed. Alas the only common standards are weights/measures and currency, everything else does vary. As an aside, I dare say that the history of importing chickens into Europe is more fascinating than most imagined, and one that still plays on even to this day.