I don't know what your deal is, but they do not, and never have sold refurbished drives in external drives. Total nonsense.
I've been buying Seagate externals and shucking them for years, and I've never once got a refurb inside. They've got normal drives in them, sometimes with slightly different firmware, but otherwise normal drives. I'm currently using 4 Seagate drives I pulled out of external boxes, an old 2TB Barracuda LP (nearly 4 years on that drive), a 3TB Barracuda XT, and two 4TB Desktop.15 drives. All are in a NAS box, and all have run perfectly.
Buying externals sometimes means you lose warranty (sometimes the bare drive will have warranty, sometime it'll be an OEM drive with no warranty), but it's a cheap way of getting the newest drives, and I personally prefer buying externals and shucking them than risk buying a bare drive that may have been mishandled somewhere along the supply chain.
Only drive I've had that's failed recently was a 1TB WD Green shucked from a Toshiba external drive years ago, but it had a hard life in it's external box before I ripped it out and used it 24/7 for a year at which point it died.