People who want to will always find a way to break the law. One radical approach would be to legalize all drugs, gambling, and prostitution. Eliminate tax deductions in favor of having a flat income tax for businesses and individuals. However if taxes on such activities are "too high" it's likely to spur a "black market".
Laws and making activities "illegal" creates crimes and criminals. Nevertheless no one wants to live in a world without order and anything goes.
However once prohibition ended that pretty much killed the moonshine and speakeasy industries. Having said that the majority of people would rather keep the status quo than to 'sell out' their morals simply for the purpose of increasing the U.S. treasury's pot.
We tend to legalize things when the vast majority of Americans feel it should be legal and impose their will on elected officals.