401ks fail the razor, because current practice has been widely known for decades, yet policymakers have chosen not to amend tax code to make them illegal. Current use may once have been against the spirit of the law, but is no longer.

(Perhaps the razor would be better worded as "would rewrite" rather than "would have written differently".)

This is why we have case law and precedent. Contrary to the old saying "two wrongs don't make a right", if everyone is doing something, it's reasonable to assume that behavior is acceptable.