Why should welfare recipients be the only one's to get drug tested?

I just recently read an article from whatweshouldknow concerning about government support or also known as Welfare. I completely agree on many parts on his comments as well as from the author of the article. To be honest, I didn't even realize that they actually have drug test for those whom are receiving benefits. I may have just been oblivious to that, because I have not really paid any close attention to such matter. Congressman Stephen Fincher made some valid points on how states should do random drug test for those whom are receiving Welfare in order to keep their benefits.  Why not have others (aside from those whom are receiving benefits) get tested as well? I strongly agree that "random" drug test should be given to employees, managers, Congressmen, and even the President himself if it seems that they are not in their own state of mind.
Overall, I think the blogger himself, has made some valid points as to why he agrees on testing others aside from those who already receive government support.