Testing recipients of government money

I had another thought about Rep. Seifert's idea to fine welfare recipients who smoke. If the idea is to prevent recipients of government money from engaging in bad habits, I have another idea as to who should be tested for drugs: legislators. After all they get lots of government money, not only in the form of salary and per diems, but in staffing, postage, and so on. So, let's subject legislators to random drug tests in order to receive their salaries. Why not?