If you place regulatory burdens on some undesirable behavior (e.g. pollution) but do not place compensatory tariffs on the import of products resulting from that exact same behavior, you're not doing anything to reduce the undesirable behavior. You're simply encouraging people to do the undesirable things elsewhere. This not only fails to accomplish the goal, but also significantly weakens the country.
The exact same problem totally undermines labor policy and unions (except those of government employees).
There really ought to be some sort of automatic mechanism for "if X is illegal/taxed/regulated then importing the result of X happening overseas is forbidden/taxed/regulated". The US already has a specific, very efficient court that does this for one specific illegal act (patent infringement); it wouldn't be difficult to expand that scope:
https://en.wikipedia.org/wiki/United_States_Court_of_Interna...