As a physician of 40 years, now retired, back in the 1980s I was the medical director of a methadone clinic and in house detox hospital. After interviewing 1000s of patients, I discovered, that the term ‘drug addicts’ is inappropriate. These people have illness, some times physical, sometimes mental, and most of the time both. They had been to many doctors only to get treated poorly, insulted and blown off. As a physician, my theme was “I am your doctor, not your judge and jury.” Yet most doctors had negative opinions about these people and as a result, they had to seek a solution on the street, which they did, street drugs.
At that time, there was around 1500 major drug dealers (guestimate), each making around 1 million per week and paying others around $200,000 a week to do the sales and distribution. Making 1 million dollars a week is a hefty paycheck and these folks are not living in the projects. They live in high class neighborhoods, and they vocalize, ‘we need to stop the drug addicts, make all drugs illegal.’ These drug dealers are making a lot of money and they want to keep drugs illegal, to keep getting the money.
A group of drugs called Opiate agonist-antagonists, nubain, buprenex, stadol, talwin, there are more, that do not have the side effect of apnea. Apnea is not breathing. In humans, opiates get in the brain, latch on to the breathing locus and cause humans to stop breathing. And death will ensue unless the person starts breathing again or another breaths for them.
The opiate agonist-antagonists have a very low apnea potential except at very high doses. When they first came out, the cost was very low, a single dose of buprenex was around 15 cents. Today, the same single dose of buprenex costs $25.00 today. As a result, the agonist-antagonists are not used, cost prohibitive.
If a person has been taking a standard opiate agonist (such as morphine, heroine, hydrocodone, oxycodone, etc) and then they take opiate agonist-antagonist, the person will go into reversal, and it can cause withdrawal. However, by taking more, the opiate agonist-antagonist can take over.
My suggestion is to put the opiate agonist-antagonist as over the counter drugs, this has the potential to satisfy those people that have a street opiate habit.
For meth habits I would suggest modafinil / andrafinil , my experience with patients is that these two products seem to satisfy the person with a meth habit and modafinil does not increase heart rate, it does not increase the blood pressure, modafinil is a selective alpha agonist, stimulating the awake center in the brain, nearly exclusively.

As far as anxiety, legalizing the benzodiazepines may be a solution, though benzodiazepines are the most addictive substances known to man. But they are safe products, with few side effects.

With billions of dollars being made within the street drug business, the only solution is to make some drugs legal, the opiate agonist-antagonists have the potential to put a big dent in street opiate business.
Modafinil and andrafinil would make a big dent in the street meth business.
Benzodiazepines would make a big dent in some of the other street drug business.

Some drugs are going to have to be over the counter, the street drug business is so large that it could turn into a society like Mexico with the drug cartels creating mayhem for anyone that gives them trouble.
The price on society is to high. As a physician, it is my opinion that most people over time will get off any drugs that they start using. As taking drugs is a monkey on one’s back and it is not a good thing. The black market is a very bad situation and making drugs legal, what ever one decides, has to be done. The risk and dangers to our society out weigh any of the problems that could occur from legalizing street drugs.