I don't know how you'd craft that law--I'm just saying they should. How to encode the spirit of the law into the letter of the law is the job for legislators.

Whenever the topic of regulating companies comes up, there's way too much fatalistic "Oh dear, we can't possibly incentivize good corporate behavior because companies are oh-so-clever and there's just no way to handle all the edge cases they will exploit!"

We'll never get anywhere at all if we simply give up the moment someone forms a shell LLC.