Who cares if people "scoff"? The point of a tax is not to affect someone's emotions. The point of a tax is to affect their behavior and collect their money. If that tax affects their planning and finances (aka they recognize it as a cost of doing business), then you achieved your goal.

While both taxes and bans are hard to enforce on small players in such cases, at least for the big players bans work more effectively. Tax is easily avoidable in any country by large players by moving the money to tax havens, and nobody wants to or can close the loopholes. So your operation is using local power and paying tax elsewhere.

When Big Co. does this at least they pay salaries, and bring some network effects in your country. Mining on the other hand is extremely resource intensive but doesn't presume any substantial local investment to make it worth it for the country.