Change only happen when the pressure is on. Allowing importation of Canadian drugs would put amazing pressure on the US sellers, even if some were counterfeit. The latter problem is solvable, at least through legitimate channels.
Insulin is now $35/month in the US because the IRA changed the law to cap the price for Medicare. Suddenly, big pharma saw a threat and now insulin is $35/month for nearly everyone, including people on regular insurance. The goverment took related action, and the phara companies read the tea leaves and suddenly dropped prices. The law going into effect and the “voluntary” price drop happened the exact same day for a reason.
Bernie didnt expect “get drugs from Canada” to be the end game. Of course he also wanted to regulate big pharma. He just understands how to apply pressure.