It's all a matter of 'the image hash was on the database, therefore OP is guilty. 10 years incarceration'.
I wouldn't want to be enabling such a system.
That can only happen if it is either (1) used by government, or (2) used by private entities in a process flow that includes reports to government.
"There exist countries with criminal justice systems with weak enough standards of proof that a false positive on a scan alone would result in prison", even if 100% true, is not a justification for a firm not making efforts to block child porn distribution on its networks. (It is, OTOH, a justification for working to reform the criminal justice systems in those countries, but that is rather far from the topic here.)
The entire argument for why verification was even an issue is that the allegedly the scan is not sufficient reason to actually believe that something is child pornoography. But whether or reviewing such a report may or may not be a crime in some jurisdiction somewhere on Earth, the certainty that arguments like that would detract from the point is the reason that of the two (moral and legal) issues raised in the post I responded to, I only said that one of them was ridiculous, and it wasn't the legal one.