My brother owned a Road King. He repeatedly told me it smoothed out at speed so I went for a pillion ride with him. It never smoothed out.
They can be quite different between models, years, and different bikes. The 94 Dyna my son dragged home vibrates so much I am waiting for the various parts to fly off in different directions. He insisted "they all do that" so I took his friend's Fatboy out and it vibrated way less, but still more than a RE.
Speaking of, don't forget you are comparing nearly-new bikes to bikes that are decades old with a lot miles and a lot of worn-out rubber.