The thretened tariffs arent on Russia, since as you point out there is little trade between USA and Russia it would be innefective in swaying the kremlin. These tariffs are instead being put on countries that trade with Russia like China, India, Brazil etc, with the hope that those countries will put pressure on Russia by proxy.

You’re gonna need to come up with a better example, when covid hit a and fewer people where buying plane tickets there where a lot fewer planes in the air. Companies usually want to be as cost effective as possible, meaning they will do the least amount of work needed to still get their customers money.

One big problem that regulation can tackle is that corporations seek to externalize as much of their costs as they can, which means the corporation won’t have to pay for the externalized cost, so they can sell their good/service cheaper, so consumption of the product increases, leading to an outsized environmental/societal cost compared to the cost of the product.