The reason peptides are largely a grey-market phenomenon is because they’re not easy to patent or otherwise monopolize through IP laws. Unlike your ordinary run-of-the mill medication, peptides are chemically simple, and often mimic or occur as endogenously-produced compounds in living animals.

They’re promising research targets from a medical POV, but the pharma industry has been systematically ignoring them for decades due to difficulties around profiting from them, as demonstrated by the current rush of GLP-1 analogs. Any firm that invests in the clinical trials to prove safety + efficacy of a given compound won’t be able to stop competitors from ripping off their work.

And to be fair, this incentive misalignment is a global issue rather than a US/Canada problem.