In a free country, doctors would be free to prescribe whatever drugs they wish to anyone for any reason. In fact, individuals should be free to buy drugs without a special government-required doctor's note.
Neither voters nor politicians watch the bureaucracy very carefully, so they respond as one might expect—advancing their own and their favorites' interests, at the expense of the public they are supposedly working for.
Americans were once harangued by government "experts" about the need to slow down on highways in order to save lives. Few listened. Today, laws demanding everyone "stay at home" may suffer a similar fate.
The state currently enjoys a vastly unbalanced share of the power within a society, such an arrangement is not in any way preordained, and the assumption that it must be betrays a narrowness of vision and a lack of historical knowledge.