[ConservingFreedom]

But in America when opium was legal, addiction was low and declining.

The very link you cited says the exact opposite.

In 1880, many drugs, including opium and cocaine, were legal — and, like some drugs today, seen as benign medicine not requiring a doctor’s care and oversight. Addiction skyrocketed.

Their own numbers give the lie to their claim - as I noted and you omitted from your reply: "In 1880 [...] there were over 400,000 opium addicts in the U.S. [...] By 1900, about one American in 200 was either a cocaine or opium addict." 400,000 in a population of 50M is one in 125 - ergo, between 1880 and 1900 addiction declined.

[DiogenesLamp]

Their own numbers give the lie to their claim

Then all you have done is to impugn the credibility of the link you yourself provided. Well done!