Drug use is for escape from life for those who cannot live life on life's terms. Anyone who feels the need to alter their consious state of thinking and discernment is seeking escape from it.
The USPS is a government agency and stamps are a part of their financial exchange for the services they render.
Government agencies were traditionally held up to higher standards in mine and previous generations.
You see nothing wrong with having drug addicts who died from overdoses on stamps sold by a Government agency?