Posting this because the summary going around does not say what the paper says, and the difference matters for how people here are using it.
The variables that decide how a cross-border order goes are declaration wording, the destination country's import rules for prescription medicines, and whether the shipment looks commercial. Personal-import allowances exist in some jurisdictions and not in others, and where they exist they are usually conditional on a prescription and a quantity limit. The failure mode is normally a seizure notice rather than anything worse, and a reshipment policy is the thing worth confirming before ordering rather than after.
Where I think it is weakest: the comparator does most of the work in how this gets reported, and it is not the comparator most people think they are citing.
The question I want answered is which of the variables in a cross-border order actually determine the outcome, and which are superstition. I have searched first, so if this is covered somewhere point me at it and I will read it.
Note on sourcing:
Figures above are from the primary publication rather than the press summary. If a number here disagrees with one you have, post yours and we will work out which of us is reading a secondary source.