Sorry, don’t get me wrong, they are most likely galvanized or at least galvanized coated. But you can usually tell when they are by the color and pattern of the galvanizing. I saw nothing to indicate this on my Spectra tank.
Problem is, and this is just me, is that I don’t trust anyone or anything. Galvanizing, if applied poorly or not thick enough (as in a mass-produced fuel tank) can easily show signs of corrosion in very short order. I would be painting the outside of the tank for sure with an epoxy base minimum to ensure adequate protection.