You do want clear rules. An extreme case of vagueness would be: pay whatever taxes you want, but we will criticize and punish you until we think you've paid enough. That would be neither efficient nor fair.
In video game terms, maybe there should be a convention of not taking advantage of exploits, but it's often unclear what's the intention of a tax rule, so fixing the exploit is better.
You do want clear rules. An extreme case of vagueness would be: pay whatever taxes you want, but we will criticize and punish you until we think you've paid enough. That would be neither efficient nor fair.
In video game terms, maybe there should be a convention of not taking advantage of exploits, but it's often unclear what's the intention of a tax rule, so fixing the exploit is better.