Fun fact: The "traditional" way of making it was extracting piperine from black pepper and reacting that with nitric acid. Nowadays it's made in other more industrial scalable ways.

https://en.wikipedia.org/wiki/Piperidine#List_of_piperidine_...

But yes, the same base precursors (and their siblings) are used to manufacture ADHD meds (ritalin/concerta), antidepressants (paxil), insect repellents (picaridin/bayrepel), hair loss medications (rogaine), allergy meds (claritin), anti-psychotics (haldol), anti-diarrhea meds (imodium), and many others. And also PCP.

So it's non-trivial to prevent. The core of the issue is that the one pot Gupta method came about in the 2000s and it made it extremely easy to manufacture fentanyl using these basic building blocks for so much of the pharma industry. Not only just making it easier to source ingredients but it took out all the steps and made the process easy as hell as well.