PillPack is basically a supply chain company - it's not an easy field to get into. I don't know if "who can ship these" is a big hurdle, though. Possibly a bigger issue is "doctors and patients are used to calling prescriptions in to pharmacies".

But the main issue with drug delivery is the need for reliability; you can't have somebody's heart medication ship out late or get lost in transit, basically ever. And if you change offerings or go out of stock on specific products (which most retailers do often), you'll quickly be seen as an unreliable way to get any kind of regular medication.

Plus, you can't let any fakes or low-quality products into your supply chain - so sourcing new suppliers is hard, but running out of suppliers for any single product is a crisis.

So being an online seller for use-as-needed prescription meds might be easy, but the bulk of the money is in people taking drugs daily, and that stuff is damned hard to offer.