Define "effective". The American war on drugs has been very effective at the thing it was intended to do (keeping the poors in their place), but not so effective at actually helping solve societal substance abuse problems
I think the problem with China is that the official metrics are likely to be skewed to portray a positive image of Chinese governance. The drug problem is probably worse, but we don't know how bad it is compared to the norm.
This gets tied to China's issues with the Opium Wars and the Century of Humiliation, so I expect any discussion in China to be very sensitive given its historic significance.
The most effective thing they’ve done is to really brainwash the public on thing like drugs. They’re very very good at controlling the narrative in China. Other than that one aspect I can’t say, but the threat of death and imprisonment for most of your life is probably genuinely terrifying
I was going to make a facetious comment like, "Yes, comrade. There is no illicit drug use in China thanks to 100% effective policy and the people's commitment to their patriotic duty."
Then I read the other comments and didn't want to look like just another shill for China. I count USA whataboutism as shilling since no one asked.