Other than that I gotta call BS on your post. There is no assumption that all poor are drug addicts. The assumption could be made that if youve got the means or $$ to get non essential drugs & alcohol, then you really shouldn't need govt money for essentials like food & housing
However the govt like anyone else should be able to put conditions on the reciept of freebies. If you want the freebies, then comply with the conditions. The ultimate goal for many of those recieving govt benefits should be to get them off the govt dole and becoming productive wage earners, wouldn't you agree? Wouldn't you also agree that they would be more employable if they were drug & alcohol free?
They already do in multiple respects. You are eliminated from getting many govt benefits such as student grants & loans if you are a druggie. Look at the privacy invasions the govt makes us go through to get on an airplane. Have you flown lately?