They didn't try it, that's the point, dummy. Methadone worked fine if you were lucky enough to be included in a program, but the vast majority of addicts can't get into one. I'm going to break my own rules on links here, and share this gem from the Conservative CATO institute.
In the United States before 1972, primary care physicians would prescribe methadone to people with OUD.<a href="
https://www.cato.org/policy-analysis/expand-access-methadone-treatment#_ednref7">7</a> Since 1972, however, only government-approved opioid treatment programs (OTPs) have been able to dispense methadone to treat OUD. The Comprehensive Drug Abuse Prevention and Control Act of 1970 required the secretary of the Department of Health and Human Services to “determine the appropriate methods of professional practice in the medical treatment of the narcotic addiction of various classes of narcotics addicts.”<a href="
https://www.cato.org/policy-analysis/expand-access-methadone-treatment#_ednref8">8</a> As a result, the Substance Abuse and Mental Health Services Administration (SAMHSA) places regulations and restrictions on organizations that seek to operate OTPs. OTPs must obtain certification from the Drug Enforcement Administration (DEA) to operate a narcotics treatment program. States must also license OTPs, imposing additional regulations and restrictions. The various layers of regulations obstruct the proliferation of OTPs.
These regulations impede access to methadone treatment by placing burdensome requirements on patients who seek it. For example, patients must wait one year from their diagnosis of OUD before they can begin receiving methadone, submit to drug testing, and take the methadone in the presence of clinic staff each day. These and other government obstacles explain why only about 400,000 people with OUD received methadone in 2019, though 1.6 million U.S. residents reported that they developed OUD that year.