The vast majority of all drug users aren't addicts and never become addicts. And that goes for all classes of drugs.
The reason recreational heroin users in particular fly under the radar to the extent that they do is threefold. For one, there's a HUGE social stigma attached to opiate use, and especially heroin. It has such a disastrous reputation that people with 'respectable' lives and careers cannot afford to be associated with it. These people go to great lengths to hide their use from anyone but a handful of other opiate-using associates.
For another, well, since their use isn't excessive they neither have nor cause problems which would make them visible as users. You won't find them in trouble with law enforcement or in need of detox or therapy. This is also why researchers only ever come across the more extreme users, ie addicts, because the only places they look for study subjects is prisons, street outreach projects and rehab facilities. T Which leads us to the third reason, it's sociology / drug researchers and doctors who drive the public narrative, and both groups have a clinical bias. 'Junkies' are all they see and interact with, so they assume that's the only kind of heroin user that exists. Since problematic users THEMSELVES typically due to their situation only associate with other addicts, that general impression only gets further cemented.
Imagine what sort of scenario we'd have if alcohol consumption was regarded like heroin. Imagine we taught people the idea that it's absolutely impossible to use alcohol responsibly or in moderation, and that EVERYONE who enjoys a pint or two is on an INEVITABLE path to ending up living under a bridge and starting the morning with half a bottle of vodka. Imagine it was totally unacceptable for someone to drink, and being found out would get you shunned from 'polite society' and fired from work etc etc.
I guarantee there'd be a lot more alcoholics (self-fulfilling prophecies are a thing), and the non-problem drinkers would be forced to conceal their habit so well that the very idea of moderate alcohol use would come to be regarded as practically mythical. If it 'can't' / 'shouldn't' exist, then it DOESN'T exist, right? ...
I can recommend two excellent books on the subject. One is a landmark study by Norman E. Zinberg, entitled "Drug, Set & Setting - The Basis for controlled Intoxicant Use", which includes users of all classes of drugs, including heroin. He emphasises that of all the people he interviewed, he had the greatest difficulty getting hold of moderate opiate users as they were so extremely guarded, and generally had to recruit heavy users (with whom casual users have to have some connection in order to get their drugs) to persuade those individuals to be willing to participate.
The other one is heroin-specific, and is called "Occasional & controlled heroin use - Not a problem?" by Hamish Warburton, Paul J. Turnbull and Mike Hough. It is available as a free download from JRF Drug and Alcohol Research Programme. It's very insightful as it includes many direct quotes from the study subjects.
PS I'm one of these casual heroin users, and I used to be an addict.
There is nothing 'irresponsible' about that report, because it merely reflects a fact.
If anything's irresponsible, it's continuing to perpetuate this entirely lopsided image of heroin and heroin users according to which user = junkie and heroin = one-way ticket to personal degradation. That's a distortion of reality and is helpful to no-one.