Because there is no such term, it is harder to talk about them as being similar. Terms used by law enforcement, such as 'substance' and 'drug', have connotations that their consumers are immature or inadequate, or mentally or emotionally ill, and that illicit substances are intrinsically dangerous and/or worthless, contrasted with licit substances, which supposedly have socially valid uses. Psychoactive Management doesn't challenge either of these views, but recommends talking about psychoactives consistently, not mistaking their legality or illegality to be a mark of intrinsic differences in value. 'PSYCHOACTIVE', a noun, is suggested as a neutral term.
"One cannot talk without words, or think without concepts." That goes through my mind when I contemplate people trying to solve problems of drug abuse, where words and concepts are missing from the dialogue. Decisions made without thoughts are likely to be thoughtless; dialogues without words are likely to be pointless. (BTW this is a sermon.) Sending messages to young people about drug abuse is like a public health program against "juvenile flu." Without including adults in the "target population," reinfection, and not taking the public health measures seriously, is likely to occur in a home where infected adults are mingling with the kids being targeted.
Or imagine a public safety program against drivers of Chevrolets speeding. Drivers of Fords who are not getting ticketed, will likely cause resentment and disrespect for the law, in communities where drivers of both vehicles are mingling. In a community where some psychoactives are consumed without penalty, and other consumption is forbidden, likely results (what in fact are happening) are disrespect for the law, and "reinfection" of inappropriate attitudes toward psychoactive consumption, namely (among licit consumers) that it's not a big problem, or (among illicit consumers) that the public health and legal authorities don't know what they're talking about.
Lack of common concepts fosters these sorts of results.
Now, one might reply, "But Chevrolets and Fords are similar, in respect to their being vehicles, but licit and illicit psychoactives are not similar. Your use of 'psychoactives' is a trick, to make them seem alike." Well, that's the point. I am saying it isn't a trick, it's a necessity, to have a common term. This is one of the main topics of Psychoactive Management: The degree to which various recreationally consumed chemicals are alike, in respect of the kinds of warnings one encounters about addiction, tolerance, toxicity, ED/LD ratio, difficulty of management, unpleasant surprises when consuming, and other negative aspects one hears about the illicit variety, and on the positive side, the potential for reasonable, responsible, positive use.
Not only the positive and negative effects are something which need conceptual linking, but the attributes of psychoactive hobbying that are relevant to Psychoactive Management, such as how one conserves one's "stash" (a "drug" term), what one does to protect the supply, quality control, and so on.
In 1984, by George Orwell, the government stifled discussion of politics and suppressed thinking that might lead to cultural revolution, by keeping certain words out of the vocabulary. The Dictionary of Newspeak accomplished this. The goal of its writers was to constanly shrink the vocabulary, in subsequent editions. Similarly -- although not done insidiously by the government-- our vocabularies with respect to psychoactive management are limited and keep us from discussing the relevant similarities of "drugs" and ______ (whatever word would mean "legal recreationally used psychoactive chemicals"), which might lead to consistent policy formation and a more enlightened understanding among citizens involved in such hobbies.