Hot Take #1: You don’t need a SCOBY to make kombucha.
Okay I’ll clarify right off the bat: if by “SCOBY” we simply mean “symbiotic culture of bacteria and yeast”, then yes, of course you need a SCOBY to make kombucha. If by “SCOBY” we mean the infamous, gelatinous raft that floats on top of the liquid, then no, you emphatically do not need a SCOBY to make kombucha.
As with “mother of vinegar”, the term SCOBY is confusing. In both vinegar and kombucha production, the micro-organisms at work form a raft that floats on the surface of the base liquid that is being fermented. In vinegar production most online sources call this raft the “mother of vinegar”, and in kombucha production it is called the SCOBY. Sources universally insist that this solid raft is required to inoculate a new batch. But that is not true.
What you really need is an active culture, and while this is certainly abundant in the raft, it is also present in the recently fermented liquid itself. Truly fresh, raw kombucha can be used to inoculate a new batch without any piece of the solid raft.
In theory you could take a bottle of unpasteurized kombucha off a grocery store shelf and use it to start your own batch. However for the culture to be active, the kombucha must be fresh. By the time commercial kombucha has been bottled it has metabolized a lot of its food, and as it sits on the shelf it stagnates and eventually is no longer active. The best way to inoculate a new batch of kombucha is with a freshly finished, homemade batch of kombucha.
If you are sad that you don’t need the raft, the good news is that if you inoculate with active culture, the raft will still form! The active cultures want to form a raft; it is essential for their biological processes and life cycle!
Hot Take #2: Kombucha does not need to contain tea to ferment properly.
The original kombucha was based on tea (the “cha” part of the name literally means tea), so if you are a prescriptive lexicographer and want to insist that kombucha must contain tea the same way cider must contain apples, that’s your right. Or if you are hoping for some kind of protected designation for tea-based kombucha, the way mayonnaise needs to contain eggs, that’s also fine. However I see arguments online insisting that the tea is an essential part of the fermentation, which is completely untrue and has been clearly disproven by forward-thinking books like The Noma Guide to Fermentation. You can have successful fermentation with everything from true tea to herbal tisane to fruit juice to coffee to maple syrup.
Hot Take #3: Kombucha should be regulated by the CFIA.
I’ve searched the Food and Drug Regulations and as far as I can see kombucha is not currently a regulated term, though it is certainly on the CFIA’s radar. I would suggest that it should be regulated, and that there should be minimum requirements for acetic acid, as there is with vinegar, and that the percent acetic acid by volume should be a label requirement.
The reason I say this is because I have purchased kombuchas that taste like dry sodas and clearly contain no acetic acid. In fact I have done acid-base titrations on them to confirm as much. This means that they are not fermented properly, and with kombucha the fermentation is kind of the whole point. Whether consumers are after the actual active cultures that are purported to improve gut-health, or the mild concentrations of acetic acid, alcohol, and other fermentation by-products, kombucha is first and foremost a fermented beverage. Not to mention that the presence of acetic acid lowers the pH and could be an important factor in the product’s safety.