Try to stay precise, you called for a 25% tax, that amount is what I was referring to. At a certain level taxes become high enough they make crime related to black markets economically viable. I suggest you look at the continuing black market in pot in "pot legal" California due to the layers of oppressive state and local taxes. 

Or just look at Alaska's dry villages. People respond to economic incentives, even necessary taxes have to be carefully tuned or the trouble of evading them will become cheaper than paying them. Add in the opportunity to actually profit from evasion and things get worse.